Light-emitting device, light-emitting apparatus, electronic device, and lighting device

ABSTRACT

A novel light-emitting device is provided. Alternatively, a light-emitting device with favorable emission efficiency is provided. Alternatively, a light-emitting device with a favorable lifetime is provided. Alternatively, a light-emitting device with a low driving voltage is provided. Provided is a light-emitting device including an anode, a cathode, and a layer including an organic compound that is positioned between the anode and the cathode, in which the layer including the organic compound includes a first layer, a second layer, and a light-emitting layer in this order from the anode side, the first layer includes a first substance and a second substance, the second layer includes a third substance, the first substance is an organic compound a HOMO level of which is higher than or equal to −5.8 eV and lower than or equal to −5.4 eV, the second substance is a substance that has an electron-acceptor property with respect to the first substance, and the third substance is an organic compound having a structure in which at least two substituents comprising carbazole rings are bonded to a naphthalene ring.

This application is a 371 of international application PCT/IB2019/052020filed on Mar. 13, 2019 which is incorporated herein by reference.

TECHNICAL FIELD

One embodiment of the present invention relates to a light-emittingdevice, a display module, a lighting module, a display device, alight-emitting apparatus, an electronic device, and a lighting device.Note that one embodiment of the present invention is not limited to theabove technical field. The technical field of one embodiment of theinvention disclosed in this specification and the like relates to anobject, a method, or a manufacturing method. One embodiment of thepresent invention relates to a process, a machine, manufacture, or acomposition (composition of matter). Specifically, examples of thetechnical field of one embodiment of the present invention disclosed inthis specification include a semiconductor device, a display device, aliquid crystal display device, a light-emitting apparatus, a lightingdevice, a power storage device, a memory device, an imaging device, adriving method thereof, and a manufacturing method thereof.

BACKGROUND ART

Light-emitting devices (organic EL devices) that use organic compoundsand utilize electroluminescence (EL) have been put into practical use.In the basic structure of such light-emitting devices, an organiccompound layer (EL layer) containing a light-emitting material isinterposed between a pair of electrodes. Carriers are injected byapplication of voltage to this device, and recombination energy of thecarriers is used, whereby light emission can be obtained from thelight-emitting material.

Such light-emitting devices are of self-light-emitting type, and haveadvantages over liquid crystal such as high visibility and no need forbacklight when used for pixels of a display; accordingly, thelight-emitting devices are suitable as flat panel display devices.Displays using such light-emitting devices are also highly advantageousin that they can be fabricated thin and lightweight. Moreover, anextremely fast response speed is also a feature.

Since light-emitting layers of such light-emitting devices can besuccessively formed two-dimensionally, planar light emission can beobtained. This feature is difficult to obtain with point light sourcestypified by incandescent lamps and LEDs or linear light sources typifiedby fluorescent lamps. Thus, light-emitting devices are also of greatutility value as planar light sources, which can be applied to lightingand the like.

Displays or lighting devices using light-emitting devices can besuitably used for a variety of electronic devices as described above,and research and development of light-emitting devices have progressedfor more favorable efficiency or lifetimes.

Patent Document 1 discloses a structure in which a hole-transportmaterial, which has a HOMO level between the HOMO level of a firsthole-injection layer and the HOMO level of a host material, is providedbetween a light-emitting layer and a first hole-transport layer incontact with the hole-injection layer.

The characteristics of light-emitting devices have been improvedremarkably, but are still insufficient to satisfy advanced requirementsfor various characteristics including efficiency and durability.

REFERENCE Patent Document

[Patent Document 1] PCT International Publication No. WO2011/065136

SUMMARY OF THE INVENTION Problems to be Solved by the Invention

Thus, an object of one embodiment of the present invention is to providea novel light-emitting device. Alternatively, an object is to provide alight-emitting element with favorable emission efficiency. Anotherobject is to provide a light-emitting device with a favorable lifetime.Another object is to provide a light-emitting device with a low drivingvoltage.

Alternatively, an object of another embodiment of the present inventionis to provide each of a light-emitting apparatus, an electronic device,and a display device with high reliability. An object of anotherembodiment of the present invention is to provide a light-emittingapparatus, an electronic device, and a display device each having lowpower consumption.

It is only necessary that at least one of the above-described objects beachieved in the present invention.

Means for Solving the Problems

One embodiment of the present invention is a light-emitting deviceincluding an anode, a cathode, and a layer including an organic compoundpositioned between the anode and the cathode. The layer including theorganic compound comprises a first layer, a second layer, and alight-emitting layer in this order from the anode side, the first layerincludes a first substance and a second substance, the second layerincludes a third substance, the first substance is an organic compound aHOMO level of which is higher than or equal to −5.8 eV and lower than orequal to −5.4 eV, the second substance is a substance that has anelectron-acceptor property with respect to the first substance, and thethird substance is an organic compound having a structure in which atleast two substituents including carbazole rings are bonded to anaphthalene ring.

Another embodiment of the present invention is a light-emitting deviceincluding an anode, a cathode, and a layer including an organic compoundpositioned between the anode and the cathode. The layer including theorganic compound includes a first layer, a second layer, and alight-emitting layer in this order from the anode side, the first layerincludes a first substance and a second substance, the second layerincludes a third substance, the first substance is aromatic amineincluding a substituent including a dibenzofuran ring or adibenzothiophene ring, the second substance is a substance that has anelectron-acceptor property with respect to the first substance, and thethird substance is an organic compound having a structure in which atleast two substituents including carbazole rings are bonded to anaphthalene ring.

Another embodiment of the present invention is a light-emitting deviceincluding an anode, a cathode, and a layer including an organic compoundpositioned between the anode and the cathode. The layer including theorganic compound includes a first layer, a second layer, and alight-emitting layer in this order from the anode side, the first layerincludes a first substance and a second substance, the second layerincludes a third substance, the first substance is aromatic monoamineincluding a naphthalene ring, the second substance is a substance thathas an electron-acceptor property with respect to the first substance,and the third substance is an organic compound having a structure inwhich at least two substituents including carbazole rings are bonded toa naphthalene ring.

Another embodiment of the present invention is a light-emitting deviceincluding an anode, a cathode, and a layer including an organic compoundpositioned between the anode and the cathode. The layer including theorganic compound includes a first layer, a second layer, and alight-emitting layer in this order from the anode side, the first layerincludes a first substance and a second substance, the second layerincludes a third substance, the first substance is aromatic monoamine inwhich a 9-fluorenyl group is bonded to nitrogen through an arylenegroup, the second substance is a substance that has an electron-acceptorproperty with respect to the first substance, and the third substance isan organic compound having a structure in which at least twosubstituents including carbazole rings are bonded to a naphthalene ring.

Another embodiment of the present invention is the light-emitting devicehaving the above structure in which the first substance is an organiccompound including an N,N-bis(4-biphenyl)amino group.

Another embodiment of the present invention is the light-emitting devicehaving the above structure in which a third layer is provided betweenthe first layer and the second layer, and the third layer includes afourth substance, and the fourth substance is an organic compound havinga hole-transport property.

Another embodiment of the present invention is the light-emitting devicehaving the above structure in which a third layer is provided betweenthe first layer and the second layer, and the third layer includes afourth substance, and the fourth substance is an organic compound a HOMOlevel of which is higher than or equal to −5.8 eV and lower than orequal to −5.4 eV.

Another embodiment of the present invention is the light-emitting devicehaving the above structure in which the fourth substance is the samesubstance as the first substance.

Another embodiment of the present invention is a light-emitting deviceincluding an anode, a cathode, and a layer including an organic compoundpositioned between the anode and the cathode. The layer including theorganic compound includes a first layer and a light-emitting layer inthis order from the anode side, the first layer includes a thirdsubstance and a second substance, the second substance is a substancethat has an electron-acceptor property with respect to the thirdsubstance, and the third substance is an organic compound having astructure in which at least two substituents including carbazole ringsare bonded to a naphthalene ring.

Another embodiment of the present invention is the light-emitting devicehaving the above structure in which the HOMO level of the thirdsubstance is higher than or equal to −5.8 eV and lower than or equal to−5.6 eV.

Another embodiment of the present invention is the light-emitting devicehaving the above structure in which the third substance is an organiccompound represented by a general formula (G1) shown below.[Chemical formula 1]A-L-B  (G1)

Note that in the general formula (G1), L represents a substituted orunsubstituted naphthalene-1,4-diyl group or a substituted orunsubstituted naphthalene-1,5-diyl group. In addition, A represents agroup represented by a general formula (gA) shown below, and Brepresents a group represented by a general formula (gB) shown below.

Note that in the general formula (gA), Ar¹ represents a substituted orunsubstituted aryl group having 6 to 13 carbon atoms in a ring. Inaddition, R¹ to R⁷ each independently represent any of hydrogen, analkyl group having 1 to 6 carbon atoms, a cycloalkyl group having 3 to 6carbon atoms, and a substituted or unsubstituted aryl group having 6 to25 carbon atoms. Note that, among them, R¹ and R², R⁴ and R⁵, R⁵ and R⁶,and R⁶ and R⁷ may be condensed to form benzene rings.

In the general formula (gB), Ar² represents a substituted orunsubstituted aryl group having 6 to 13 carbon atoms in a ring. Inaddition, R¹¹ to R¹⁷ each independently represent any of hydrogen, analkyl group having 1 to 6 carbon atoms, a cycloalkyl group having 3 to 6carbon atoms, and a substituted or unsubstituted aryl group having 6 to25 carbon atoms. Note that R¹¹ and R¹², R¹⁴ and R¹⁵, R¹⁵ and R¹⁶, andR¹⁶ and R¹⁷ may be condensed to form benzene rings.

Another embodiment of the present invention is the organic compoundhaving the above structure in which the third substance is representedby a general formula (G1) shown below.[Chemical formula 3]A-L-B  (G1)

Note that in the general formula (G1), L represents a group representedby a general formula (gL-1) shown below or a general formula (gL-2)shown below, A represents a group represented by a general formula (gA)shown below, and B represents a group represented by a general formula(gB) shown below.

Note that in the general formula (gL-1), R⁴¹ to R⁴⁶ each independentlyrepresent any of hydrogen, an alkyl group having 1 to 6 carbon atoms, acycloalkyl group having 3 to 6 carbon atoms, and a substituted orunsubstituted aryl group having 6 to 13 carbon atoms in a ring.

In the general formula (gL-2), R⁵¹ to R⁵⁶ each independently representany of hydrogen, an alkyl group having 1 to 6 carbon atoms, a cycloalkylgroup having 3 to 6 carbon atoms, and a substituted or unsubstitutedaryl group having 6 to 13 carbon atoms in a ring.

Note that in the general formula (gA), Ar¹ represents a substituted orunsubstituted aryl group having 6 to 13 carbon atoms in a ring. Inaddition, R¹ to R⁷ each independently represent any of hydrogen, analkyl group having 1 to 6 carbon atoms, a cycloalkyl group having 3 to 6carbon atoms, and a substituted or unsubstituted aryl group having 6 to25 carbon atoms. Note that, among them, R¹ and R², R⁴ and R⁵, R⁵ and R⁶,and R⁶ and IC may be condensed to form benzene rings.

In the general formula (gB), Ar² represents a substituted orunsubstituted aryl group having 6 to 13 carbon atoms in a ring.Furthermore, R¹¹ to R¹⁷ each independently represent any of hydrogen, analkyl group having 1 to 6 carbon atoms, a cycloalkyl group having 3 to 6carbon atoms, and a substituted or unsubstituted aryl group having 6 to25 carbon atoms. Note that R¹¹ and R¹², R¹⁴ and R¹⁵, R¹⁵ and R¹⁶, andR¹⁶ and R^(1′) may be condensed to form benzene rings.

Another embodiment of the present invention is the light-emitting devicehaving the above structure in which the third substance is3,3′-(naphthalene-1,4-diyl)bis(9-phenyl-9H-carbazole) or3,3′-(naphthalene-1,5-diyl)bis(9-phenyl-9H-carbazole).

Another embodiment of the present invention is the light-emitting devicehaving the above structure in which the second substance is an organiccompound.

Another embodiment of the present invention is an electronic devicehaving the above structure, which includes a sensor, an operationbutton, a speaker, or a microphone.

Another embodiment of the present invention is a light-emittingapparatus having the above structure, which includes a transistor or asubstrate.

Another embodiment of the present invention is a lighting device havingthe above structure, which includes a housing.

Note that the light-emitting apparatus in this specification includes animage display device using a light-emitting device. The light-emittingapparatus includes, in some cases, a module in which a light-emittingdevice is provided with a connector such as an anisotropic conductivefilm or a TCP (Tape Carrier Package), a module in which a printed wiringboard is provided at the end of a TCP, or a module in which an IC(integrated circuit) is directly mounted on a light-emitting device by aCOG (Chip On Glass) method. Furthermore, in some cases, lightingequipment or the like includes the light-emitting apparatus.

Effect of the Invention

In one embodiment of the present invention, a novel light-emittingdevice can be provided. Alternatively, a light-emitting device with afavorable lifetime can be provided. Alternatively, a light-emittingdevice with favorable emission efficiency can be provided.

Alternatively, in another embodiment of the present invention, alight-emitting apparatus, an electronic device, and a display devicewith high reliability can each be provided. In another embodiment of thepresent invention, a light-emitting apparatus, an electronic device, anda display device each having low power consumption can be provided.

Note that the descriptions of the effects do not disturb the existenceof other effects. Note that one embodiment of the present invention doesnot need to have all these effects. Effects other than these will beapparent from and can be derived from the description of thespecification, the drawings, the claims, and the like.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1A-1C are schematic diagrams of light-emitting devices.

FIGS. 2A and 2B are conceptual diagrams of an active matrixlight-emitting apparatus.

FIGS. 3A and 3B are conceptual diagrams of active matrix light-emittingapparatuses.

FIG. 4 is a schematic diagram of an active matrix light-emittingapparatus.

FIGS. 5A and 5B are conceptual diagrams of a passive matrixlight-emitting apparatus.

FIGS. 6A and 6B are diagrams illustrating a lighting device.

FIGS. 7A-7C are diagrams illustrating electronic devices.

FIGS. 8A-8C are diagrams illustrating electronic devices.

FIG. 9 is a diagram illustrating a lighting device.

FIG. 10 is a diagram illustrating a lighting device.

FIG. 11 is a diagram illustrating in-vehicle display devices andlighting devices.

FIGS. 12A and 12B are diagrams illustrating an electronic device.

FIGS. 13A-13C are diagrams illustrating an electronic device.

FIG. 14 is luminance-current density characteristics of a light-emittingdevice 1 and a comparative light-emitting device 1.

FIG. 15 is current efficiency—luminance characteristics of thelight-emitting device 1 and the comparative light-emitting device 1.

FIG. 16 is luminance-voltage characteristics of the light-emittingdevice 1 and the comparative light-emitting device 1.

FIG. 17 is current-voltage characteristics of the light-emitting element1 and the comparative light-emitting element 1.

FIG. 18 is external quantum efficiency—luminance characteristics of thelight-emitting device 1 and the comparative light-emitting device 1.

FIG. 19 is emission spectra of the light-emitting device 1 and thecomparative light-emitting device 1.

FIG. 20 is normalized luminance—temporal change characteristics of thelight-emitting device 1 and the comparative light-emitting device 1.

FIG. 21 is luminance-current density characteristics of a light-emittingdevice 2 and a comparative light-emitting device 2.

FIG. 22 is current efficiency—luminance characteristics of thelight-emitting device 2 and the comparative light-emitting device 2.

FIG. 23 is luminance-voltage characteristics of the light-emittingdevice 2 and the comparative light-emitting device 2.

FIG. 24 is current-voltage characteristics of the light-emitting element2 and the comparative light-emitting element 2.

FIG. 25 is external quantum efficiency—luminance characteristics of thelight-emitting device 2 and the comparative light-emitting device 2.

FIG. 26 is emission spectra of the light-emitting device 2 and thecomparative light-emitting device 2.

FIG. 27 is normalized luminance—temporal change characteristics of thelight-emitting device 2 and the comparative light-emitting device 2.

FIG. 28 is luminance-current density characteristics of a light-emittingdevice 3 and a comparative light-emitting device 3.

FIG. 29 is current efficiency—luminance characteristics of thelight-emitting device 3 and the comparative light-emitting device 3.

FIG. 30 is luminance-voltage characteristics of the light-emittingdevice 3 and the comparative light-emitting device 3.

FIG. 31 is current-voltage characteristics of the light-emitting element3 and the comparative light-emitting element 3.

FIG. 32 is external quantum efficiency—luminance characteristics of thelight-emitting device 3 and the comparative light-emitting device 3.

FIG. 33 is emission spectra of the light-emitting device 3 and thecomparative light-emitting device 3.

FIG. 34 is normalized luminance—temporal change characteristics of thelight-emitting device 3 and the comparative light-emitting device 3.

FIG. 35 is luminance-current density characteristics of a light-emittingdevice 4 and a comparative light-emitting device 4.

FIG. 36 is current efficiency—luminance characteristics of thelight-emitting device 4 and the comparative light-emitting device 4.

FIG. 37 is luminance-voltage characteristics of the light-emittingdevice 4 and the comparative light-emitting device 4.

FIG. 38 is current-voltage characteristics of the light-emitting element4 and the comparative light-emitting element 4.

FIG. 39 is external quantum efficiency—luminance characteristics of thelight-emitting device 4 and the comparative light-emitting device 4.

FIG. 40 is emission spectra of the light-emitting device 4 and thecomparative light-emitting device 4.

FIG. 41 is normalized luminance—temporal change characteristics of thelight-emitting device 4 and the comparative light-emitting device 4.

FIG. 42 is normalized luminance—temporal change characteristics oflight-emitting devices and comparative light-emitting devices.

FIGS. 43A and 43B are ¹H NMR charts of YGTBilBP.

FIG. 44 is an absorption spectrum and an emission spectrum of YGTBilBPin a toluene solution.

FIG. 45 is an absorption spectrum and an emission spectrum of YGTBilBPin a thin film state.

FIGS. 46A and 46B are¹H NMR charts of4-[4’-(carbazol-9-yl)biphenyl-4-yl]-4’-biphenylamine.

FIGS. 47A and 47B are ¹H NMR charts of YGTBiβNB.

FIG. 48 is an absorption spectrum and an emission spectrum of YGTBiβNBin a toluene solution.

FIG. 49 is an absorption spectrum and an emission spectrum of YGTBiβNBin a thin film state.

FIGS. 50A and 50B are¹H NMR charts of BBAFLP.

FIGS. 51A and 51B are¹H NMR charts of BBAFLBi.

FIGS. 52A and 52B are¹H NMR charts of mBBAFLP.

FIGS. 53A and 53B are¹H NMR charts of mpBBAFLBi.

FIG. 54 is an absorption spectrum and an emission spectrum of mpBBAFLBiin a toluene solution.

FIG. 55 is an absorption spectrum and an emission spectrum of mpBBAFLBiin a thin film state.

FIGS. 56A and 56B are ¹H NMR charts of TPBiAβNB.

FIG. 57 is an absorption spectrum and an emission spectrum of TPBiAβNBin a toluene solution.

FIG. 58 is an absorption spectrum and an emission spectrum of TPBiAβNBin a thin film state.

FIGS. 59A and 59B are ¹H NMR charts of TPBiAβNBi.

FIG. 60 is an absorption spectrum and an emission spectrum of TPBiAβNBiin a toluene solution.

FIG. 61 is an absorption spectrum and an emission spectrum of TPBiAβNBiin a thin film state.

FIGS. 62A and 62B are¹H NMR charts of BBAPβNB-03.

FIG. 63 is an absorption spectrum and an emission spectrum of BBAPβNB-03in a toluene solution.

FIG. 64 is an absorption spectrum and an emission spectrum of BBAPβNB-03in a thin film state.

FIGS. 65A and 65B are ¹H NMR charts of YGTBilBP-02.

FIG. 66 is an absorption spectrum and an emission spectrum ofYGTBilBP-02 in a toluene solution.

FIG. 67 is an absorption spectrum and an emission spectrum ofYGTBilBP-02 in a thin film state.

MODE FOR CARRYING OUT THE INVENTION

Embodiments of the present invention are described in detail below withreference to drawings. Note that the present invention is not limited tothe following description, and it will be readily appreciated by thoseskilled in the art that modes and details of the present invention canbe modified in various ways without departing from the spirit and scopeof the present invention. Thus, the present invention should not beconstrued as being limited to the descriptions in the followingembodiments.

Embodiment 1

FIG. 1 shows diagrams illustrating light-emitting devices of oneembodiment of the present invention. The light-emitting devices of oneembodiment of the present invention each include a first electrode 101,a second electrode 102, and an EL layer 103, and the EL layer includes ahole-injection layer 111, a hole-transport layer 112, and alight-emitting layer 113.

In addition to them an electron-transport layer 114 and anelectron-injection layer 115 are shown in the EL layer 103 in FIG. 1(A)and FIG. 1(B); however, the structure of the light-emitting device isnot limited thereto.

The hole-injection layer 111 contains a first substance and a secondsubstance. The first substance is a substance the HOMO level of which ishigher than or equal to −5.8 eV and lower than or equal to −5.4 eV. Thesecond substance is a substance exhibiting an electron-acceptor propertywith respect to the first substance.

A third substance contained in the hole-transport layer 112 is anorganic compound having a structure in which at least two substituentsincluding carbazole rings are bonded to a naphthalene ring.

The light-emitting device of the present invention, which has theabove-described structure, can be a light-emitting device that hasfavorable emission efficiency and a long lifetime.

The first substance is preferably an organic compound having ahole-transport property. Alternatively, aromatic amine having asubstituent that includes a dibenzofuran ring or a dibenzothiophenering, aromatic monoamine that includes a naphthalene ring, or aromaticmonoamine in which a 9-fluorenyl group is bonded to nitrogen of aminethrough an arylene group may be used. Note that it is preferable thatthe first substance be a substance including an N,N-bis(4-biphenyl)aminogroup because a light-emitting device with a favorable lifetime can bemanufactured. As specific examples of the above-described firstsubstance,N-(4-biphenyl)-6,N-diphenylbenzo[b]naphtho[1,2-d]furan-8-amine(abbreviation: BnfABP),N,N-bis(4-biphenyl)-6-phenylbenzo[b]naphtho[1,2-d]furan-8-amine(abbreviation: BBABnf),4,4′-bis(6-phenylbenzo[b]naphtho[1,2-d]furan-8-yl)-4″-phenyltriphenylamine(abbreviation: BnfBB1BP),N,N-bis(4-biphenyl)benzo[b]naphtho[1,2-d]furan-6-amine (abbreviation:BBABnf(6)), N,N-bis(4-biphenyl)benzo[b]naphtho[1,2-d]furan-8-amine(abbreviation: BBABnf(8)),N,N-bis(4-biphenyl)benzo[b]naphtho[2,3-d]furan-4-amine (abbreviation:BBABnf(II)(4)), N,N-bis[4-(dibenzofuran-4-yl)phenyl]-4-amino-p-terphenyl(abbreviation: DBfBB1TP),N-[4-(dibenzothiophen-4-yl)phenyl]-N-phenyl-4-biphenylamine(abbreviation: ThBA1BP), 4-(2-naphthyl)-4′,4″-diphenyltriphenylamine(abbreviation: BBAβNB),4-[4-(2-naphthyl)phenyl]-4′,4″-diphenyltriphenylamine (abbreviation:BBAβNBi), 4,4′-diphenyl-4″-(6;1′-binaphthyl-2-yl)triphenylamine(abbreviation: BBAαNβNB),4,4′-diphenyl-4″-(7;1′-binaphthyl-2-yl)triphenylamine (abbreviation:BBAαNβNB-03), 4,4′-diphenyl-4″-(7-phenyl)naphthyl-2-yltriphenylamine(abbreviation: BBAPβNB-03),4,4′-diphenyl-4″-(6;2′-binaphthyl-2-yl)triphenylamine (abbreviation:BBA(βN2)B), 4,4′-diphenyl-4″-(7;2′-binaphthyl-2-yl)triphenylamine(abbreviation: BBA(βN2)B-03),4,4′-diphenyl-4″-(4;2′-binaphthyl-1-yl)triphenylamine (abbreviation:BBAβNαNB), 4,4′-diphenyl-4″-(5;2′-binaphthyl-1-yl)triphenylamine(abbreviation: BBAβNαNB-02),4-(4-biphenylyl)-4′-(2-naphthyl)-4″-phenyltriphenylamine (abbreviation:TPBiAβNB),4-(3-biphenylyl)-4′-[4-(2-naphthyl)phenyl]-4″-phenyltriphenylamine(abbreviation: mTPBiAβNBi),4-(4-biphenylyl)-4′-[4-(2-naphthyl)phenyl]-4″-phenyltriphenylamine(abbreviation: TPBiAβNBi), 4-phenyl-4′-(1-naphthyl)triphenylamine(abbreviation: αNBA1BP), 4,4′-bis(1-naphthyl)triphenylamine(abbreviation: αNBB1BP),4,4′-diphenyl-4″-[4′-(carbazol-9-yl)biphenyl-4-yl]triphenylamine(abbreviation: YGTBi1BP),4′-[4-(3-phenyl-9H-carbazol-9-yl)phenyl]tris(1,1′-biphenyl-4-yl)amine(abbreviation: YGTBi1BP-02),4-diphenyl-4′-(2-naphthyl)-4″-{9-(4-biphenylyl)carbazol}triphenylamine(abbreviation: YGTBiβNB),N-[4-(9-phenyl-9H-carbazol-3-yl)phenyl]-N-[4-(1-naphthyl)phenyl]-9,9′-spirobi(9H-fluoren)-2-amine(abbreviation: PCBNBSF),N,N-bis(4-biphenylyl)-9,9′-spirobi[9H-fluoren]-2-amine (abbreviation:BBASF), N,N-bis(1,1′-biphenyl-4-yl)-9,9′-spirobi[9H-fluoren]-4-amine(abbreviation: BBASF(4)),N-(1,1′-biphenyl-2-yl)-N-(9,9-dimethyl-9H-fluoren-2-yl)-9,9′-spiro-bi(9H-fluoren)-4-amine(abbreviation: oFBiSF),N-(4-biphenyl)-N-(dibenzofuran-4-yl)-9,9-dimethyl-9H-fluoren-2-amine(abbreviation: FrBiF),N-[4-(1-naphthyl)phenyl]-N-[3-(6-phenyldibenzofuran-4-yl)phenyl]-1-naphthylamine(abbreviation: mPDBfBNBN),4-phenyl-4′-(9-phenylfluoren-9-yl)triphenylamine (abbreviation: BPAFLP),4-phenyl-3′-(9-phenylfluoren-9-yl)triphenylamine (abbreviation:mBPAFLP), 4-phenyl-4′-[4-(9-phenylfluoren-9-yl)phenyl]triphenylamine(abbreviation: BPAFLBi),4-phenyl-4′-(9-phenyl-9H-carbazol-3-yl)triphenylamine (abbreviation:PCBA1BP), 4,4′-diphenyl-4″-(9-phenyl-9-H-carbazol-3-yl)triphenylamine(abbreviation: PCBBi1BP),4-(1-naphthyl)-4′-(9-phenyl-9H-carbazol-3-yl)-triphenylamine(abbreviation: PCBANB),4,4′-di(1-naphthyl)-4″-(9-phenyl-9H-carbazol-3-yl)triphenylamine(abbreviation: PCBNBB),N-phenyl-N-[4-(9-phenyl-9H-carbazol-3-yl)phenyl]-spiro-9,9′-bifluoren-2-amine(abbreviation: PCBASF), and the like can be given.

The second substance may be an inorganic compound or an organiccompound. As the second substance, transition metal oxide, oxide ofmetal that belongs to Group 4 to Group 8 of the periodic table, or anorganic compound including an electron-withdrawing group (specifically,a halogen group such as a fluoro group or a cyano group), or the likecan be used, and a substance exhibiting an electron-acceptor propertywith respect to the first substance may be selected from such substancesas appropriate.

As the transition metal oxide or the oxide of metal belonging to Group 4to Group 8 of the periodic table that can be used as the secondsubstance, vanadium oxide, niobium oxide, tantalum oxide, chromiumoxide, molybdenum oxide, tungsten oxide, manganese oxide, rhenium oxide,titanium oxide, ruthenium oxide, zirconium oxide, hafnium oxide, andsilver oxide are preferable because they exhibit a high acceptorproperty. Among them, molybdenum oxide is particularly preferablebecause of its high stability in the air, low hygroscopicity, and highhandiness.

As the organic compound including an electron-withdrawing group (ahalogen group or a cyano group) that can be used as the secondsubstance, 7,7,8,8-tetracyano-2,3,5,6-tetrafluoroquinodimethane(abbreviation: F₄-TCNQ), chloranil,2,3,6,7,10,11-hexacyano-1,4,5,8,9,12-hexaazatriphenylene (abbreviation:HAT-CN), 1,3,4,5,7,8-hexafluorotetracyano-naphthoquinodimethane(abbreviation: F6-TCNNQ),2-(7-dicyanomethylene-1,3,4,5,6,8,9,10-octafluoro-7H-pyren-2-ylidene)malononitrile,and the like can be given. A compound in which electron-withdrawinggroups are bonded to a condensed aromatic ring having a plurality ofhetero atoms, such as HAT-CN, is particularly preferable because it isthermally stable. A [3]radialene derivative including anelectron-withdrawing group (in particular, a halogen group such as afluoro group, or a cyano group) has a very high electron-acceptingproperty and thus is preferable; specifically,α,α′,α″-1,2,3-cyclopropanetriylidenetris[4-cyano-2,3,5,6-tetrafluorobenzeneacetonitrile],α,α′,α″-1,2,3-cyclopropanetriylidenetris[2,6-dichloro-3,5-difluoro-4-(trifluoromethyl)benzeneacetonitrile],α,α′,α″-1,2,3-cyclopropanetriylidenetris[2,3,4,5,6-pentafluorobenzeneacetonitrile],and the like can be given.

Note that the electron-acceptor property of an inorganic compound suchas molybdenum oxide tends to be stronger than those of theabove-described organic compounds. In a light-emitting device in whichthe second substance is an organic compound, an increase in the drivingvoltage and a decrease in the lifetime are likely to occur when the HOMOlevel of the first substance is deep (e.g., deeper than −5.4 eV);however, the light-emitting device of the present invention also has acharacteristic in that such problems are less likely to occur.

The HOMO level of the third substance is preferably higher than or equalto −5.8 eV and lower than or equal to −5.6 eV, in which case holeinjection into a light-emitting layer host having a deep HOMO level isperformed smoothly. This is particularly important in the case where ablue fluorescent layer is used as the light-emitting layer. For example,in the case where the light-emitting layer contains a host material anda light-emitting material and the light-emitting material exhibits bluefluorescence, the band gap of the host material needs to be wider thanthat of a blue color, and as a result, the HOMO level thereof tends tobe deep. Therefore, it is preferable for hole injection into thelight-emitting layer that the HOMO level of the third substance behigher than or equal to −5.8 eV and lower than or equal to −5.6 eV. Notethat as such a wide-gap host material, an organic compound having ananthracene skeleton can be given typically.

Note that when the LUMO level of the third substance is higher than orequal to −2.4 eV, preferably higher than or equal to −2.2 eV, loss ofelectrons from the light-emitting layer can be effectively prevented,leading to an improvement in the emission efficiency. For the samereason, a difference between the LUMO level of the third substance andthe LUMO level of the host material is preferably greater than or equalto 0.3 eV, further preferably greater than or equal to 0.5 eV.

In the case where the host material has an anthracene skeleton and acarbazole skeleton, in particular, an anthracene skeleton and adibenzocarbazole skeleton, the host material has high electron mobility.Therefore, the driving voltage can be reduced while the light-emittinglayer tends to have excess electrons correspondingly, and a decrease inthe reliability might be caused because of a reduction in therecombination region, loss of electrons from the light-emitting layer,and the like. However, this problem can be overcome because such a thirdsubstance described above has a favorable hole-injection property to thelight-emitting layer in the light-emitting device of one embodiment ofthe present invention.

As the third substance, organic compounds represented by a generalformula (G1) shown below are preferable. These compounds are compoundsthat have deep HOMO levels and have not only excellent hole-injectionproperties to the light-emitting layer but also high durability againstelectrons. Accordingly, a light-emitting device with favorablereliability can be provided.[Chemical formula 6]A-L-B  (G1)

Note that in the general formula (G1), L represents a substituted orunsubstituted naphthalene-1,4-diyl group or a substituted orunsubstituted naphthalene-1,5-diyl group. The substituted orunsubstituted naphthalene-1,4-diyl group or the substituted orunsubstituted naphthalene-1,5-diyl group can also be represented by ageneral formula (gL-1) or a general formula (gL-2) shown below.

Note that in the general formula (gL-1), R⁴¹ to R⁴⁶ each independentlyrepresent any of hydrogen, an alkyl group having 1 to 6 carbon atoms, acycloalkyl group having 3 to 6 carbon atoms, and a substituted orunsubstituted aryl group having 6 to 13 carbon atoms in a ring.

In the general formula (gL-2), R⁵¹ to R⁵⁶ each independently representany of hydrogen, an alkyl group having 1 to 6 carbon atoms, a cycloalkylgroup having 3 to 6 carbon atoms, and a substituted or unsubstitutedaryl group having 6 to 13 carbon atoms in a ring.

Note that it is preferable that R⁴¹ to R⁴⁶ or R⁵¹ to R⁵⁶ be allhydrogen, in which case synthesis is facilitated.

In the general formula (G1), A represents a group represented by ageneral formula (gA) shown below, and B represents a group representedby a general formula (gB) shown below.

Note that in the general formula (gA), Ar¹ represents a substituted orunsubstituted aryl group having 6 to 13 carbon atoms in a ring.Furthermore, le to IC each independently represent any of hydrogen, analkyl group having 1 to 6 carbon atoms, a cycloalkyl group having 3 to 6carbon atoms, and a substituted or unsubstituted aryl group having 6 to25 carbon atoms. Note that R¹ and R², R⁴ and R⁵, R⁵ and R⁶, and R⁶ andR⁷ may be condensed to form benzene rings.

In the general formula (gB), AP represents a substituted orunsubstituted aryl group having 6 to 13 carbon atoms in a ring.Furthermore, R¹¹ to R¹⁷ each independently represent any of hydrogen, analkyl group having 1 to 6 carbon atoms, a cycloalkyl group having 3 to 6carbon atoms, and a substituted or unsubstituted aryl group having 6 to25 carbon atoms. Note that R¹¹ and R¹², R¹⁴ and R¹⁵, R¹⁵ and R¹⁶, andR¹⁶ and R¹⁷ may be condensed to form benzene rings.

R¹ to R⁷, R¹¹ to R¹⁷, R²¹ to R²⁴, R²⁵ to R²⁸, and R³¹ to R³⁸ eachindependently represent hydrogen, an alkyl group having 1 to 6 carbonatoms, a cycloalkyl group having 3 to 6 carbon atoms, or a substitutedor unsubstituted aryl group having 6 to 25 carbon atoms; a methyl group,an ethyl group, a propyl group, an isopropyl group, an n-butyl group, asec-butyl group, an isobutyl group, a tert-butyl group, a pentyl group,a hexyl group, and the like can be given as the alkyl group having 1 to6 carbon atoms; a cyclopropyl group, a cyclobutyl group, a cyclopentylgroup, a cyclohexyl group, and the like can be given as the cycloalkylgroup having 3 to 6 carbon atoms; a phenyl group, a biphenyl group, anaphthyl group, a phenanthryl group, an anthryl group, a triphenylenylgroup, a fluorenyl group, a 9,9-diphenylfluorenyl group, a9,9-spirobifluorenyl group, and the like can be given as the substitutedor unsubstituted aryl group having 6 to 25 carbon atoms. Note that inorder to prevent emergence of an electron-transport property, of thosegroups described above, a group that does not contain polyacene havingthree or more rings is preferable.

In the case where the substituted or unsubstituted aryl group having 6to 25 carbon atoms has a substituent, an alkyl group having 1 to 6carbon atoms, a cycloalkyl group having 3 to 6 carbon atoms, or an arylgroup having 6 to 13 carbon atoms can be used as the substituent.Specific examples of them include a methyl group, an ethyl group, apropyl group, an isopropyl group, a tert-butyl group, a hexyl group, acyclopropyl group, a cyclohexyl group, a phenyl group, a tolyl group, anaphthyl group, and a biphenyl group.

R⁴¹ to R⁴⁶ and R⁵¹ to R⁵⁶ each independently represent hydrogen, analkyl group having 1 to 6 carbon atoms, a cycloalkyl group having 3 to 6carbon atoms, or a substituted or unsubstituted aryl group having 6 to13 carbon atoms in a ring; specifically, a methyl group, an ethyl group,a propyl group, an isopropyl group, a butyl group, a tert-butyl group, apentyl group, a hexyl group, and the like can be given as the alkylgroup having 1 to 6 carbon atoms; a cyclopropyl group, a cyclohexylgroup, and the like can be given as the cycloalkyl group having 3 to 6carbon atoms; a phenyl group, a biphenyl group, a naphthyl group, aphenanthryl group, an anthryl group, a fluorenyl group, and the like canbe given as the substituted or unsubstituted aryl group having 6 to 13carbon atoms in a ring.

In the case where the substituted or unsubstituted aryl group having 6to 13 carbon atoms in a ring has a substituent, an alkyl group having 1to 6 carbon atoms, a cycloalkyl group having 3 to 6 carbon atoms, or anaryl group having 6 to 13 carbon atoms can be used as the substituent.Specific examples of them include a methyl group, an ethyl group, apropyl group, an isopropyl group, a tert-butyl group, a hexyl group, acyclopropyl group, a cyclohexyl group, a phenyl group, a tolyl group, anaphthyl group, and a biphenyl group.

Furthermore, Ar¹ and Ar² each independently represent a substituted orunsubstituted aryl group having 6 to 13 carbon atoms in a ring;specifically, a phenyl group, a naphthyl group, a biphenyl group, afluorenyl group, a dimethylfluorenyl group, a diphenylfluorenyl group, atert-butylphenyl group, a tolyl group, a trimethylphenyl group, and thelike can be given.

Note that a light-emitting device in which the third substance is3,3′-(naphthalene-1,4-diyl)bis(9-phenyl-9H-carbazole) or3,3′-(naphthalene-1,5-diyl)bis(9-phenyl-9H-carbazole) is preferablebecause of its high emission efficiency.

Note that it is preferable that the third substance, that is, theorganic compound having a structure in which at least two substituentsincluding carbazole rings are bonded to a naphthalene ring do notinclude a triarylamine skeleton in order to prevent the HOMO level frombeing too shallow.

Note that the hole-transport layer 112 may have a two-layer structure.In that case, the organic compound having the structure in which atleast two substituents including carbazole rings are bonded to anaphthalene ring is preferably used in a layer in contact with thelight-emitting layer of the two layers. At this time, deterioration ofthe device can be small when the electron-transport property of theorganic compound is small; thus, it is preferable that the organiccompound do not have polyacene that has three or more rings in amolecular.

Furthermore, in that case, the other layer on the hole-injection layerside is a layer that contains an organic compound having ahole-transport property, and the organic compound having ahole-transport property is preferably an organic compound the HOMO levelof which is higher than or equal to −5.8 eV and lower than or equal to−5.4 eV. It is further preferable that the organic compound be the samesubstance as the first substance.

Embodiment 2

Next, examples of specific structures and materials of theabove-described light-emitting device are described. As described above,the light-emitting device of one embodiment of the present inventionincludes, between the pair of electrodes of the first electrode 101 andthe second electrode 102, the EL layer 103 including a plurality oflayers; the EL layer 103 includes at least the hole-injection layer 111,the hole-transport layer 112, and the light-emitting layer 113 from thefirst electrode 101 side.

There is no particular limitation on the other layers included in the ELlayer 103, and various layer structures such as a hole-injection layer,a hole-transport layer, an electron-transport layer, anelectron-injection layer, a carrier-blocking layer, an exciton-blockinglayer, and a charge-generation layer can be employed.

The first electrode 101 is preferably formed using a metal, an alloy, ora conductive compound having a high work function (specifically, 4.0 eVor more), a mixture thereof, or the like. Specifically, for example,indium oxide-tin oxide (ITO: Indium Tin Oxide), indium oxide-tin oxidecontaining silicon or silicon oxide, indium oxide-zinc oxide, indiumoxide containing tungsten oxide and zinc oxide (IWZO), and the like canbe given. These conductive metal oxide films are usually formed by asputtering method but may also be formed by application of a sol-gelmethod or the like. An example of the formation method is a method inwhich an indium oxide-zinc oxide film is formed by a sputtering methodusing a target in which 1 to 20 wt % zinc oxide is added to indiumoxide. Indium oxide containing tungsten oxide and zinc oxide (IWZO) canalso be formed by a sputtering method using a target containing 0.5 to 5wt % tungsten oxide and 0.1 to 1 wt % zinc oxide with respect to indiumoxide. Alternatively, gold (Au), platinum (Pt), nickel (Ni), tungsten(W), chromium (Cr), molybdenum (Mo), iron (Fe), cobalt (Co), copper(Cu), palladium (Pd), a nitride of a metal material (such as titaniumnitride), and the like can be given. Graphene can also be used. Notethat although the typical substances that have a high work function andare used as a material used for forming the anode are listed above, acomposite material of an organic compound having a hole-transportproperty and a substance exhibiting an electron-accepting property withrespect to the organic compound is used for the hole-injection layer 111of one embodiment of the present invention; thus, an electrode materialcan be selected regardless of the work function.

In this embodiment, two kinds of stacked-layer structures of the ELlayer 103 are described: the structure including the electron-transportlayer 114 and the electron-injection layer 115 in addition to thehole-injection layer 111, the hole-transport layer 112, and thelight-emitting layer 113 as illustrated in FIG. 1(A); and the structureincluding the electron-transport layer 114, the electron-injection layer115, and a charge-generation layer 116 in addition to the hole-injectionlayer 111, the hole-transport layer 112, and the light-emitting layer113 as illustrated in FIG. 1(B). Materials forming the layers arespecifically described below.

The hole-injection layer 111 is a layer containing the first substancethat is an organic compound the HOMO level of which is higher than orequal to −5.8 eV and lower than or equal to −5.4 eV and the secondsubstance that has an electron-acceptor property with respect to thefirst substance. Although the second substance may be either aninorganic compound or an organic compound in the structure of oneembodiment of the present invention, the structure is particularlysuitable when the second substance is an organic compound.

The first substance and the second substance are described in Embodiment1 in detail; thus, repeated description is omitted. Refer to thecorresponding description.

The formation of the hole-injection layer 111 can improve thehole-injection property, whereby a light-emitting device having a lowdriving voltage can be obtained. The organic compound having anelectron-acceptor property is an easy-to-use material becauseevaporation is easy and its film can be easily formed.

The hole-transport layer 112 contains a hole-transport material. Thehole-transport material preferably has a hole mobility of 1×10⁻⁶ cm²/Vsor more. In one embodiment of the present invention, as a material ofthe hole-transport layer, an organic compound having a structure inwhich at least two substituents including carbazole rings are bonded toa naphthalene ring is used. Note that the organic compound having astructure in which at least two substituents including carbazole ringsare bonded to a naphthalene ring is described in detail in Embodiment 1;thus, repeated description is omitted.

The hole-transport layer 112 may have a two-layer structure. In thatcase, the organic compound having the structure in which at least twosubstituents including carbazole rings are bonded to a naphthalene ringis preferably used in a layer in contact with the light-emitting layerof the two layers. At this time, deterioration of the device can besmall when the electron-transport property of the organic compound issmall; thus, it is preferable that the organic compound do not havepolyacene that has three or more rings in a molecular.

Furthermore, the other layer is a layer that contains an organiccompound having a hole-transport property, and the organic compoundhaving a hole-transport property is preferably an organic compound theHOMO level of which is higher than or equal to −5.8 eV and lower than orequal to −5.4 eV. It is further preferable that the organic compound bethe same substance as the first substance.

The light-emitting layer 113 is a layer containing the host material andthe light-emitting material. The light-emitting material may befluorescent substances, phosphorescent substances, substances exhibitingthermally activated delayed fluorescence (TADF), or other light-emittingmaterials. Furthermore, it may be a single layer or be formed of aplurality of layers including different light-emitting materials. Notethat one embodiment of the present invention is more preferably used inthe case where the light-emitting layer 113 is a layer that exhibitsfluorescence, specifically, a layer that exhibits blue fluorescence.

Examples of a material that can be used as a fluorescent substance inthe light-emitting layer 113 are as follows. Fluorescent substancesother than those given below can also be used.

For example, 5,6-bis[4-(10-phenyl-9-anthryl)phenyl]-2,2′-bipyridine(abbreviation: PAP2BPy),5,6-bis[4′-(10-phenyl-9-anthryl)biphenyl-4-yl]-2,2′-bipyridine(abbreviation: PAPP2BPy),N,N′-diphenyl-N,N′-bis[4-(9-phenyl-9H-fluoren-9-yl)phenyl]pyrene-1,6-diamine(abbreviation: 1,6FLPAPrn),N,N′-bis(3-methylphenyl)-N,N′-bis[3-(9-phenyl-9H-fluoren-9-yl)phenyl]-pyrene-1,6-diamine(abbreviation: 1,6mMemFLPAPrn),N,N′-bis[4-(9H-carbazol-9-yl)phenyl]-N,N′-diphenyl stilbene-4,4′-diamine(abbreviation: YGA2S),4-(9H-carbazol-9-yl)-4′-(10-phenyl-9-anthryl)triphenylamine(abbreviation: YGAPA),4-(9H-carbazol-9-yl)-4′-(9,10-diphenyl-2-anthryl)triphenylamine(abbreviation: 2YGAPPA),N,9-diphenyl-N-[4-(10-phenyl-9-anthryl)phenyl]-9H-carbazol-3-amine(abbreviation: PCAPA), perylene, 2,5,8,11-tetra-tert-butylperylene(abbreviation: TBP),4-(10-phenyl-9-anthryl)-4′-(9-phenyl-9H-carbazol-3-yl)triphenylamine(abbreviation: PCBAPA),N,N″-(2-tert-butylanthracene-9,10-diyldi-4,1-phenylene)bis[N,N′,N′-triphenyl-1,4-phenylenediamine](abbreviation: DPABPA),N,9-diphenyl-N-[4-(9,10-diphenyl-2-anthryl)phenyl]-9H-carbazol-3-amine(abbreviation: 2PCAPPA),N-[4-(9,10-diphenyl-2-anthryl)phenyl]-triphenyl-1,4-phenylenedi amine(abbreviation: 2DPAPPA),N,N,N′,N′,N″,N″,N′″,N′″-octaphenyldibenzo[g,p]chrysene-2,7,10,15-tetraamine(abbreviation: DBC1), coumarin 30,N-(9,10-diphenyl-2-anthryl)-N,9-diphenyl-9H-carbazol-3-amine(abbreviation: 2PCAPA),N-[9,10-bis(1,1′-biphenyl-2-yl)-2-anthryl]-N,9-diphenyl-9H-carbazol-3-amine(abbreviation: 2PCABPhA),N-(9,10-diphenyl-2-anthryl)-N,N′,N′-triphenyl-1,4-phenylenediamine(abbreviation: 2DPAPA),N-[9,10-bis(1,1′-biphenyl-2-yl)-2-anthryl]-N,N′,N′-triphenyl-1,4-phenylenediamine(abbreviation: 2DPABPhA),9,10-bis(1,1′-biphenyl-2-yl)-N-[4-(9H-carbazol-9-yl)phenyl]-N-phenylanthracen-2-amine(abbreviation: 2YGABPhA), N,N,9-triphenylanthracen-9-amine(abbreviation: DPhAPhA), coumarin 545T, N,N′-diphenylquinacridone(abbreviation: DPQd), rubrene,5,12-bis(1,1′-biphenyl-4-yl)-6,11-diphenyltetracene (abbreviation: BPT),2-(2-{2-[4-(dimethylamino)phenyl]ethenyl}-6-methyl-4H-pyran-4-ylidene)propanedinitrile(abbreviation: DCM1),2-{2-methyl-6-[2-(2,3,6,7-tetrahydro-1H,5H-benzo[ij]quinolizin-9-yl)ethenyl]-4H-pyran-4-ylidene}propanedinitrile(abbreviation: DCM2),N,N,N′,N′-tetrakis(4-methylphenyl)tetracene-5,11-diamine (abbreviation:p-mPhTD),7,14-diphenyl-N,N,N′,N′-tetrakis(4-methylphenyl)acenaphtho[1,2-a]fluoranthene-3,10-diamine(abbreviation: p-mPhAFD),2-{2-isopropyl-6-[2-(1,1,7,7-tetramethyl-2,3,6,7-tetrahydro-1H,5H-benzo[ij]quinolizin-9-yl)ethenyl]-4H-pyran-4-ylidene}propanedinitrile(abbreviation: DCJTI),2-{2-tert-butyl-6-[2-(1,1,7,7-tetramethyl-2,3,6,7-tetrahydro-1H,5H-benzo[ij]quinolizin-9-yl)ethenyl]-4H-pyran-4-ylidene}propanedinitrile(abbreviation: DCJTB),2-(2,6-bis{2-[4-(dimethylamino)phenyl]ethenyl}-4H-pyran-4-ylidene)propanedinitrile(abbreviation: BisDCM),2-{2,6-bis[2-(8-methoxy-1,1,7,7-tetramethyl-2,3,6,7-tetrahydro-1H,5H-benzo[ij]quinolizin-9-yl)ethenyl]-4H-pyran-4-ylidene}propanedinitrile(abbreviation: BisDCJTM), andN,N′-diphenyl-N,N′-(1,6-pyrene-diyl)bis[(6-phenylbenzo[b]naphtho[1,2-d]furan)-8-amine](abbreviation: 1,6BnfAPrn-03) can be given. In particular, a condensedaromatic diamine compound typified by a pyrenediamine compound such as1,6FLPAPrn, 1,6mMemFLPAPrn, and 1,6BnfAPrn-03 is preferable because ofits high hole-trapping property, high emission efficiency, and highreliability.

Examples of a material that can be used as a phosphorescent substance inthe light-emitting layer 113 are as follows.

An organometallic iridium complex having a 4H-triazole skeleton, such astris{2-[5-(2-methylphenyl)-4-(2,6-dimethylphenyl)-4H-1,2,4-triazol-3-yl-κN2]phenyl-κC}iridium(III)(abbreviation: [Ir(mpptz-dmp)₃]),tris(5-methyl-3,4-diphenyl-4H-1,2,4-triazolato)iridium(III)(abbreviation: [Ir(Mptz)₃]), ortris[4-(3-biphenyl)-5-isopropyl-3-phenyl-4H-1,2,4-triazolato]iridium(III)(abbreviation: [Ir(iPrptz-3b)₃]), an organometallic iridium complexhaving a 1H-triazole skeleton, such astris[3-methyl-1-(2-methylphenyl)-5-phenyl-1H-1,2,4-triazolato]iridium(III)(abbreviation: [Ir(Mptz1-mp)₃]) ortris(1-methyl-5-phenyl-3-propyl-1H-1,2,4-triazolato)iridium(III)(abbreviation: [Ir(Prptz1-Me)₃]), an organometallic iridium complexhaving an imidazole skeleton, such asfac-tris[1-(2,6-diisopropylphenyl)-2-phenyl-1H-imidazole]iridium(III)(abbreviation: [Ir(iPrpmi)₃]) ortris[3-(2,6-dimethylphenyl)-7-methylimidazo[1,2-f]phenanthridinato]iridium(III)(abbreviation: [Ir(dmpimpt-Me)₃]), and an organometallic iridium complexin which a phenylpyridine derivative having an electron-withdrawinggroup is a ligand, such asbis[2-(4′,6′-difluorophenyl)pyridinato-N,C²′]iridium(III)tetrakis(1-pyrazolyl)borate(abbreviation: FIr6),bis[2-(4′,6′-difluorophenyl)pyridinato-N,C²′]iridium(III)picolinate(abbreviation: FIrpic),bis{2-[3′,5′-bis(trifluoromethyl)phenyl]pyridinato-N,C²′}iridium(III)picolinate (abbreviation: [Ir(CF₃ppy)₂(pic)]), orbis[2-(4′,6′-difluorophenyl)pyridinato-N,C²′]iridium(III)acetylacetonate(abbreviation: FIracac) can be given. These are compounds exhibitingblue phosphorescence, and are compounds having an emission peak at 440nm to 520 nm.

Furthermore, an organometallic iridium complex having a pyrimidineskeleton, such as tris(4-methyl-6-phenylpyrimidinato)iridium(III)(abbreviation: [Ir(mppm)₃]),tris(4-t-butyl-6-phenylpyrimidinato)iridium(III) (abbreviation:[Ir(tBuppm)₃]),(acetylacetonato)bis(6-methyl-4-phenylpyrimidinato)iridium(III)(abbreviation: [Ir(mppm)₂(acac)]),(acetylacetonato)bis(6-tert-butyl-4-phenylpyrimidinato)iridium(III)(abbreviation: [Ir(tBuppm)₂(acac)]),(acetylacetonato)bis[6-(2-norbornyl)-4-phenylpyrimidinato]iridium(III)(abbreviation: [Ir(nbppm)₂(acac)]),(acetylacetonato)bis[5-methyl-6-(2-methylphenyl)-4-phenylpyrimidinato]iridium(III)(abbreviation: [Ir(mpmppm)₂(acac)]), or(acetylacetonato)bis(4,6-diphenylpyrimidinato)iridium(III)(abbreviation: [Ir(dppm)₂(acac)]), an organometallic iridium complexhaving a pyrazine skeleton, such as(acetylacetonato)bis(3,5-dimethyl-2-phenylpyrazinato)iridium(III)(abbreviation: [Ir(mppr-Me)₂(acac)]) or(acetylacetonato)bis(5-isopropyl-3-methyl-2-phenylpyrazinato)iridium(III)(abbreviation: [Ir(mppr-iPr)₂(acac)]), an organometallic iridium complexhaving a pyridine skeleton, such astris(2-phenylpyridinato-N,C²′)iridium(III) (abbreviation: [Ir(ppy)₃]),bis(2-phenylpyridinato-N,C²′)iridium(III)acetylacetonate (abbreviation:[Ir(ppy)₂(acac)]), bis(benzo[h]quinolinato)iridium(III)acetylacetonate(abbreviation: [Ir(bzq)₂(acac)]), tris(benzo[h]quinolinato)iridium(III)(abbreviation: [Ir(bzq)₃]), tris(2-phenylquinolinato-N,C²′)iridium(III)(abbreviation: [Ir(pq)₃]), or bis(2-phenylquinolinato-N,C²′)iridium(III)acetylacetonate (abbreviation: [Ir(pq)₂(acac)]), and a rare earth metalcomplex such as tris(acetylacetonato) (monophenanthroline)terbium(III)(abbreviation: [Tb(acac)₃(Phen)]) can be given. These are mainlycompounds exhibiting green phosphorescence, and have an emission peak at500 nm to 600 nm. Note that an organometallic iridium complex having apyrimidine skeleton is particularly preferable because of itsdistinctively high reliability and emission efficiency.

Furthermore, an organometallic iridium complex having a pyrimidineskeleton, such as(diisobutyrylmethanato)bis[4,6-bis(3-methylphenyl)pyrimidinato]iridium(III)(abbreviation: [Ir(5mdppm)₂(dibm)]),bis[4,6-bis(3-methylphenyl)pyrimidinato](dipivaloylmethanato)iridium(III)(abbreviation: [Ir(5mdppm)₂(dpm)]), orbis[4,6-di(naphthalen-1-yl)pyrimidinato](dipivaloylmethanato)iridium(III)(abbreviation: [Ir(d1npm)₂(dpm)]), an organometallic iridium complexhaving a pyrazine skeleton, such as(acetylacetonato)bis(2,3,5-triphenylpyrazinato)iridium(III)(abbreviation: [Ir(tppr)₂(acac)]),bis(2,3,5-triphenylpyrazinato)(dipivaloylmethanato)iridium(III)(abbreviation: [Ir(tppr)₂(dpm)]), or(acetylacetonato)bis[2,3-bis(4-fluorophenyl)quinoxalinato]iridium(III)(abbreviation: [Ir(Fdpq)₂(acac)]), an organometallic iridium complexhaving a pyridine skeleton, such astris(1-phenylisoquinolinato-N,C²′)iridium(III) (abbreviation:[Ir(piq)₃]) orbis(1-phenylisoquinolinato-N,C²′)iridium(III)acetylacetonate(abbreviation: [Ir(piq)₂(acac)]), a platinum complex such as2,3,7,8,12,13,17,18-octaethyl-21H,23H-porphyrin platinum(II)(abbreviation: PtOEP), and a rare earth metal complex such astris(1,3-diphenyl-1,3-propanedionato) (monophenanthroline)europium(III)(abbreviation: [Eu(DBM)₃(Phen)]) ortris[1-(2-thenoyl)-3,3,3-trifluoroacetonato](monophenanthroline)europium(III)(abbreviation: [Eu(TTA)₃(Phen)]) can be given. These are compoundsexhibiting red phosphorescence, and have an emission peak at 600 nm to700 nm. Furthermore, from the organometallic iridium complex having apyrazine skeleton, red light emission with favorable chromaticity can beobtained.

Besides the above-described phosphorescent compounds, other knownphosphorescent materials may be selected and used.

As the TADF material, a fullerene, a derivative thereof, an acridine, aderivative thereof, an eosin derivative, or the like can be used. Otherexamples include a metal-containing porphyrin containing magnesium (Mg),zinc (Zn), cadmium (Cd), tin (Sn), platinum (Pt), indium (In), palladium(Pd), or the like. Examples of the metal-containing porphyrin include aprotoporphyrin-tin fluoride complex (SnF₂(Proto IX)), amesoporphyrin-tin fluoride complex (SnF₂(Meso IX)), ahematoporphyrin-tin fluoride complex (SnF₂(Hemato IX)), a coproporphyrintetramethyl ester-tin fluoride complex (SnF₂(Copro III-4Me)), anoctaethylporphyrin-tin fluoride complex (SnF₂(OEP)), anetioporphyrin-tin fluoride complex (SnF₂(Etio I)), and anoctaethylporphyrin-platinum chloride complex (PtCl₂(OEP)), which arerepresented by the following structural formulae.

Alternatively, a heterocyclic compound having both of a π-electron richheteroaromatic ring and a π-electron deficient heteroaromatic ring thatis represented by the following structural formulae, such as2-(biphenyl-4-yl)-4,6-bis(12-phenylindolo[2,3-a]carbazol-11-yl)-1,3,5-triazine(abbreviation: PIC-TRZ),9-(4,6-diphenyl-1,3,5-triazin-2-yl)-9′-phenyl-9H,9′H-3,3′-bicarbazole(abbreviation: PCCzTzn),9-[4-(4,6-diphenyl-1,3,5-triazin-2-yl)phenyl]-9′-phenyl-9H,9′H-3,3′-bicarbazole(abbreviation: PCCzPTzn),2-[4-(10H-phenoxazine-10-yl)phenyl]-4,6-diphenyl-1,3,5-triazine(abbreviation: PXZ-TRZ),3-[4-(5-phenyl-5,10-dihydrophenazin-10-yl)phenyl]-4,5-diphenyl-1,2,4-triazole(abbreviation: PPZ-3TPT),3-(9,9-dimethyl-9H-acridin-10-yl)-9H-xanthen-9-one (abbreviation:ACRXTN), bis[4-(9,9-dimethyl-9,10-dihydroacridine)phenyl]sulfone(abbreviation: DMAC-DPS), or10-phenyl-10H,10′H-spiro[acridin-9,9′-anthracen]-10′-one (abbreviation:ACRSA) can be used. The heterocyclic compound is preferable because ofhaving both a high electron-transport property and a high hole-transportproperty owing to a π-electron rich heteroaromatic ring and a π-electrondeficient heteroaromatic ring. Note that a substance in which theπ-electron rich heteroaromatic ring and the π-electron deficientheteroaromatic ring are directly bonded to each other is particularlypreferable because the donor property of the π-electron richheteroaromatic ring and the acceptor property of the π-electrondeficient heteroaromatic ring are both increased and the energydifference between the S1 level and the T1 level becomes small, so thatthermally activated delayed fluorescence can be obtained with highefficiency. Note that an aromatic ring to which an electron-withdrawinggroup such as a cyano group is bonded may be used instead of theπ-electron deficient heteroaromatic ring.

As the host material in the light-emitting layer, a variety ofcarrier-transport materials such as a material having anelectron-transport property and a material having a hole-transportproperty can be used.

As a material having a hole-transport property, a compound having anaromatic amine skeleton, such as4,4′-bis[N-(1-naphthyl)-N-phenylamino]biphenyl (abbreviation: NPB),N,N′-bis(3-methylphenyl)-N,N′-diphenyl-[1,1′-biphenyl]-4,4′-diamine(abbreviation: TPD),4,4′-bis[N-(spiro-9,9′-bifluoren-2-yl)-N-phenylamino]biphenyl(abbreviation: BSPB), 4-phenyl-4′-(9-phenylfluoren-9-yl)triphenylamine(abbreviation: BPAFLP), 4-phenyl-3′-(9-phenylfluoren-9-yl)triphenylamine(abbreviation: mBPAFLP),4-phenyl-4′-(9-phenyl-9H-carbazol-3-yl)triphenylamine (abbreviation:PCBA1BP), 4,4′-diphenyl-4″-(9-phenyl-9H-carbazol-3-yl)triphenylamine(abbreviation: PCBBi1BP),4-(1-naphthyl)-4′-(9-phenyl-9H-carbazol-3-yl)-triphenylamine(abbreviation: PCBANB),4,4′-di(1-naphthyl)-4″-(9-phenyl-9H-carbazol-3-yl)triphenylamine(abbreviation: PCBNBB),9,9-dimethyl-N-phenyl-N-[4-(9-phenyl-9H-carbazol-3-yl)phenyl]fluoren-2-amine(abbreviation: PCBAF), orN-phenyl-N-[4-(9-phenyl-9H-carbazol-3-yl)phenyl]-spiro-9,9′-bifluoren-2-amine(abbreviation: PCBASF), a compound having a carbazole skeleton, such as1,3-bis(N-carbazolyl)benzene (abbreviation: mCP),4,4′-di(N-carbazolyl)biphenyl (abbreviation: CBP),3,6-bis(3,5-diphenylphenyl)-9-phenylcarbazole (abbreviation: CzTP), or3,3′-bis(9-phenyl-9H-carbazole) (abbreviation: PCCP), a compound havinga thiophene skeleton, such as4,4′,4″-(benzene-1,3,5-triyl)tri(dibenzothiophene) (abbreviation:DBT3P-II),2,8-diphenyl-4-[4-(9-phenyl-9H-fluoren-9-yl)phenyl]dibenzothiophene(abbreviation: DBTFLP-III), or4-[4-(9-phenyl-9H-fluoren-9-yl)phenyl]-6-phenyldibenzothiophene(abbreviation: DBTFLP-IV), and a compound having a furan skeleton, suchas 4,4′,4″-(benzene-1,3,5-triyl)tri(dibenzofuran) (abbreviation:DBF3P-II) or4-{3-[3-(9-phenyl-9H-fluoren-9-yl)phenyl]phenyl}dibenzofuran(abbreviation: mmDBFFLBi-II) can be given. Among the above, the compoundhaving an aromatic amine skeleton and the compound having a carbazoleskeleton are preferable because these have favorable reliability, havehigh hole-transport properties, and contribute to a reduction in drivingvoltage.

As the material having an electron-transport property, for example, ametal complex such as bis(10-hydroxybenzo[h]quinolinato)beryllium(II)(abbreviation: BeBq₂),bis(2-methyl-8-quinolinolato)(4-phenylphenolato)aluminum(III)(abbreviation: BAlq), bis(8-quinolinolato)zinc(II) (abbreviation: Znq),bis[2-(2-benzoxazolyl)phenolato]zinc(II) (abbreviation: ZnPBO), orbis[2-(2-benzothiazolyl)phenolato]zinc(II) (abbreviation: ZnBTZ), aheterocyclic compound having a polyazole skeleton, such as2-(4-biphenylyl)-5-(4-tert-butylphenyl)-1,3,4-oxadiazole (abbreviation:PBD), 3-(4-biphenylyl)-4-phenyl-5-(4-tert-butylphenyl)-1,2,4-triazole(abbreviation: TAZ),1,3-bis[5-(p-tert-butylphenyl)-1,3,4-oxadiazol-2-yl]benzene(abbreviation: OXD-7),9-[4-(5-phenyl-1,3,4-oxadiazol-2-yl)phenyl]-9H-carbazole (abbreviation:CO11), 2,2′,2″-(1,3,5-benzenetriyl)tris(1-phenyl-1H-benzimidazole)(abbreviation: TPBI), or2-[3-(dibenzothiophen-4-yl)phenyl]-1-phenyl-1H-benzimidazole(abbreviation: mDBTBIm-II), a heterocyclic compound having a diazineskeleton, such as2-[3-(dibenzothiophen-4-yl)phenyl]dibenzo[f,h]quinoxaline (abbreviation:2mDBTPDBq-II),2-[3′-(dibenzothiophen-4-yl)biphenyl-3-yl]dibenzo[f,h]quinoxaline(abbreviation: 2mDBTBPDBq-II),2-[3′-(9H-carbazol-9-yl)biphenyl-3-yl]dibenzo[f,h]quinoxaline(abbreviation: 2mCzBPDBq), 4,6-bis[3-(phenanthren-9-yl)phenyl]pyrimidine(abbreviation: 4,6mPnP2Pm), or4,6-bis[3-(4-dibenzothienyl)phenyl]pyrimidine (abbreviation:4,6mDBTP2Pm-II), and a heterocyclic compound having a pyridine skeleton,such as 3,5-bis[3-(9H-carbazol-9-yl)phenyl]pyridine (abbreviation:35DCzPPy) or 1,3,5-tri[3-(3-pyridyl)-phenyl]benzene (abbreviation:TmPyPB) can be given. Among the above, the heterocyclic compound havinga diazine skeleton and the heterocyclic compound having a pyridineskeleton have favorable reliability and thus are preferable. Inparticular, the heterocyclic compound having a diazine (pyrimidine orpyrazine) skeleton has a high electron-transport property andcontributes to a reduction in driving voltage.

In the case where a fluorescent substance is used as the light-emittingmaterial, a material having an anthracene skeleton is suitable for thehost material. The use of a substance having an anthracene skeleton as ahost material for a fluorescent substance makes it possible to achieve alight-emitting layer with favorable emission efficiency and durability.As the substance having an anthracene skeleton that is used as the hostmaterial, a substance having a diphenylanthracene skeleton, inparticular, a substance having a 9,10-diphenylanthracene skeleton, ispreferable because of its chemical stability. The host materialpreferably has a carbazole skeleton because the hole-injection andhole-transport properties are improved; further preferably, the hostmaterial has a benzocarbazole skeleton in which a benzene ring isfurther condensed to carbazole because the HOMO level thereof isshallower than that of carbazole by approximately 0.1 eV and thus holesenter the host material easily. In particular, the host material havinga dibenzocarbazole skeleton is preferable because its HOMO level isshallower than that of carbazole by approximately 0.1 eV so that holesenter the host material easily, the hole-transport property is improved,and the heat resistance is increased. Accordingly, a substance that hasboth a 9,10-diphenylanthracene skeleton and a carbazole skeleton (or abenzocarbazole skeleton or a dibenzocarbazole skeleton) is furtherpreferable as the host material. Note that in terms of thehole-injection and hole-transport properties described above, instead ofa carbazole skeleton, a benzofluorene skeleton or a dibenzo fluoreneskeleton may be used. Examples of such a substance include9-phenyl-3-[4-(10-phenyl-9-anthryl)phenyl]-9H-carbazole (abbreviation:PCzPA), 3-[4-(1-naphthyl)-phenyl]-9-phenyl-9H-carbazole (abbreviation:PCPN), 9-[4-(10-phenyl-9-anthracenyl)phenyl]-9H-carbazole (abbreviation:CzPA), 7-[4-(10-phenyl-9-anthryl)phenyl]-7H-dibenzo[c,g]carbazole(abbreviation: cgDBCzPA),6-[3-(9,10-diphenyl-2-anthryl)phenyl]-benzo[b]naphtho[1,2-d]furan(abbreviation: 2mBnfPPA), and9-phenyl-10-{4-(9-phenyl-9H-fluoren-9-yl)-biphenyl-4′-yl}-anthracene(abbreviation: FLPPA). In particular, CzPA, cgDBCzPA, 2mBnfPPA, andPCzPA are preferably selected because they exhibit favorablecharacteristics.

Note that a host material may be a material of a mixture of a pluralityof kinds of substances; in the case of using a mixed host material, itis preferable to mix a material having an electron-transport propertywith a material having a hole-transport property. When the materialhaving an electron-transport property is mixed with the material havinga hole-transport property, the transport property of the light-emittinglayer 113 can be easily adjusted and a recombination region can beeasily controlled. The ratio of the content of the material having ahole-transport property to the content of the material having anelectron-transport property may be the material having a hole-transportproperty: the material having an electron-transport property=1:9 to 9:1.

An exciplex may be formed by these mixed materials. A combination ispreferably selected so as to form an exciplex that exhibits lightemission overlapping with the wavelength of a lowest-energy-sideabsorption band of a light-emitting material, because energy can betransferred smoothly and light emission can be efficiently obtained. Theuse of the structure is preferable because the driving voltage is alsobe reduced.

The electron-transport layer 114 is a layer containing a substancehaving an electron-transport property. As the substance having anelectron-transport property, it is possible to use any of theabove-listed substances having electron-transport properties that can beused as the host material.

As the electron-injection layer 115, a layer containing an alkali metal,an alkaline earth metal, or a compound thereof, such as lithium fluoride(LiF), cesium fluoride (CsF), or calcium fluoride (CaF₂), may beprovided between the electron-transport layer 114 and the secondelectrode 102. For example, an electride or a layer that is formed usinga substance having an electron-transport property and that includes analkali metal, an alkaline earth metal, or a compound thereof can be usedas the electron-injection layer 115. Examples of the electride include asubstance in which electrons are added at high concentration to a mixedoxide of calcium and aluminum.

Instead of the electron-injection layer 115, the charge-generation layer116 may be provided. The charge-generation layer 116 refers to a layercapable of injecting holes into a layer in contact therewith on thecathode side and injecting electrons into a layer in contact therewithon the anode side when supplied with a potential. The charge-generationlayer 116 includes at least a P-type layer 117. The P-type layer 117 ispreferably formed using the composite materials given above as thematerial that can form the hole-injection layer 111. The P-type layer117 may be formed by stacking a film containing the above acceptormaterial as a material included in the composite material and a filmcontaining the above hole-transport material. When a potential isapplied to the P-type layer 117, electrons are injected into theelectron-transport layer 114 and holes are injected into the secondelectrode 102 that is a cathode; thus, the light-emitting deviceoperates.

Note that one or both of an electron-relay layer 118 and anelectron-injection buffer layer 119 are preferably provided in thecharge-generation layer 116 in addition to the P-type layer 117.

The electron-relay layer 118 contains at least a substance having anelectron-transport property and has a function of preventing aninteraction between the electron-injection buffer layer 119 and theP-type layer 117 to transfer electrons smoothly. The LUMO level of thesubstance having an electron-transport property contained in theelectron-relay layer 118 is preferably between the LUMO level of anacceptor substance in the P-type layer 117 and the LUMO level of asubstance contained in a layer of the electron-transport layer 114 incontact with the charge-generation layer 116. A specific energy level ofthe LUMO level of the substance having an electron-transport propertyused for the electron-relay layer 118 may be higher than or equal to−5.0 eV, preferably higher than or equal to −5.0 eV and lower than orequal to −3.0 eV. Note that as the substance having anelectron-transport property used for the electron-relay layer 118, aphthalocyanine-based material or a metal complex having a metal-oxygenbond and an aromatic ligand is preferably used.

For the electron-injection buffer layer 119, a substance having a highelectron-injection property, such as an alkali metal, an alkaline earthmetal, a rare earth metal, or a compound thereof (an alkali metalcompound (including an oxide such as lithium oxide, a halide, and acarbonate such as lithium carbonate or cesium carbonate), an alkalineearth metal compound (including an oxide, a halide, and a carbonate), ora rare earth metal compound (including an oxide, a halide, and acarbonate)), can be used.

In the case where the electron-injection buffer layer 119 is formed soas to contain the substance having an electron-transport property and adonor substance, an organic compound such as tetrathianaphthacene(abbreviation: TTN), nickelocene, or decamethylnickelocene can be usedas the donor substance, as well as an alkali metal, an alkaline earthmetal, a rare earth metal, a compound thereof (an alkali metal compound(including an oxide such as lithium oxide, a halide, and a carbonatesuch as lithium carbonate or cesium carbonate), an alkaline earth metalcompound (including an oxide, a halide, and a carbonate), or a rareearth metal compound (including an oxide, a halide, and a carbonate)).Note that as the substance having an electron-transport property, amaterial similar to the above-described material forming theelectron-transport layer 114 can be used for the formation.

As a substance forming the second electrode 102, a metal, an alloy, anelectrically conductive compound, or a mixture thereof having a low workfunction (specifically, 3.8 eV or less) or the like can be used. Asspecific examples of such a cathode material, elements belonging toGroup 1 or Group 2 of the periodic table, such as alkali metals, e.g.,lithium (Li) and cesium (Cs)), magnesium (Mg), calcium (Ca), andstrontium (Sr), alloys containing these (MgAg and AlLi), rare earthmetals such as europium (Eu) and ytterbium (Yb), alloys containing theserare earth metals, and the like can be given. However, when theelectron-injection layer is provided between the second electrode 102and the electron-transport layer, as the second electrode 102, a varietyof conductive materials such as Al, Ag, ITO, or indium oxide-tin oxidecontaining silicon or silicon oxide can be used regardless of their workfunctions. Films of these conductive materials can be formed by a dryprocess such as a vacuum evaporation method or a sputtering method, aninkjet method, a spin coating method, or the like. Alternatively, thefilms may be formed by a wet process using a sol-gel method or a wetprocess using a paste of a metal material.

Various methods can be used as a method for forming the EL layer 103regardless of whether it is a dry process or a wet process. For example,a vacuum evaporation method, a gravure printing method, an offsetprinting method, a screen printing method, an ink-jet method, a spincoating method, or the like may be used.

Different deposition methods may be used to form the electrodes or thelayers described above.

The structure of the layers provided between the first electrode 101 andthe second electrode 102 is not limited to the above-describedstructure. However, a structure is preferable in which a light-emittingregion where holes and electrons recombine is provided at a positionaway from the first electrode 101 and the second electrode 102 so as toprevent quenching caused by the proximity of the light-emitting regionand a metal used for electrodes and carrier-injection layers.

Furthermore, in order to inhibit energy transfer from an excitongenerated in the light-emitting layer, it is preferable to form thehole-transport layer and the electron-transport layer that are incontact with the light-emitting layer 113, particularly acarrier-transport layer closer to the recombination region in thelight-emitting layer 113, using the light-emitting material of thelight-emitting layer or a substance having a wider band gap than thelight-emitting material included in the light-emitting layer.

Next, an embodiment of a light-emitting device with a structure where aplurality of light-emitting units is stacked (also referred to as astacked-type device or a tandem device) will be described with referenceto FIG. 1(C). This light-emitting device is a light-emitting deviceincluding a plurality of light-emitting units between an anode and acathode. One light-emitting unit has substantially the same structure asthat of the EL layer 103, which is illustrated in FIG. 1(A). In otherwords, the light-emitting device illustrated in FIG. 1(C) can be calleda light-emitting device including a plurality of light-emitting units,and the light-emitting device illustrated in FIG. 1(A) or FIG. 1(B) canbe called a light-emitting device including one light-emitting unit.

In FIG. 1(C), a first light-emitting unit 511 and a secondlight-emitting unit 512 are stacked between an anode 501 and a cathode502, and a charge-generation layer 513 is provided between the firstlight-emitting unit 511 and the second light-emitting unit 512. Theanode 501 and the cathode 502 correspond, respectively, to the firstelectrode 101 and the second electrode 102 in FIG. 1(A), and the samesubstance as what is given in the description for FIG. 1(A) can be used.Furthermore, the first light-emitting unit 511 and the secondlight-emitting unit 512 may have the same structure or differentstructures.

The charge-generation layer 513 has a function of injecting electronsinto one of the light-emitting units and injecting holes into the otherof the light-emitting units when a voltage is applied to the anode 501and the cathode 502. That is, in FIG. 1(C), any layer can be used as thecharge-generation layer 513 as long as the layer injects electrons intothe first light-emitting unit 511 and injects holes into the secondlight-emitting unit 512 in the case where a voltage is applied such thatthe potential of the anode is higher than that of the cathode.

The charge-generation layer 513 is preferably formed with a structuresimilar to that of the charge-generation layer 116 described withreference to FIG. 1(B). A composite material of an organic compound anda metal oxide has an excellent carrier-injection property and anexcellent carrier-transport property; thus, low-voltage driving andlow-current driving can be achieved. Note that in the case where theanode-side surface of a light-emitting unit is in contact with thecharge-generation layer 513, the charge-generation layer 513 can alsoserve as a hole-injection layer of the light-emitting unit; therefore, ahole-injection layer is not necessarily provided in the light-emittingunit.

In the case where the electron-injection buffer layer 119 is provided inthe charge-generation layer 513, the electron-injection buffer layer 119serves as an electron-injection layer in the light-emitting unit on theanode side; therefore, an electron-injection layer is not necessarilyformed in the light-emitting unit on the anode side.

The light-emitting device having two light-emitting units is describedwith reference to FIG. 1(C); however, the same can also be applied to alight-emitting device in which three or more light-emitting units arestacked. With a plurality of light-emitting units partitioned by thecharge-generation layer 513 between a pair of electrodes as in thelight-emitting element according to this embodiment, it is possible toachieve an element that can emit light with the current density kept lowand has a longer lifetime. Moreover, a light-emitting device that can bedriven at a low voltage and has low power consumption can be achieved.

Furthermore, when emission colors of the light-emitting units aredifferent, light emission of a desired color can be obtained from thelight-emitting device as a whole. For example, in a light-emittingdevice having two light-emitting units, emission colors of red and greenare obtained in the first light-emitting unit and an emission color ofblue is obtained in the second light-emitting unit, whereby alight-emitting device that emits white light as the whole light-emittingdevice can be obtained.

The above-described layers and electrodes such as the EL layer 103, thefirst light-emitting unit 511, the second light-emitting unit 512, andthe charge-generation layer can be formed by a method such as anevaporation method (including a vacuum evaporation method), a dropletdischarge method (also referred to as an ink-jet method), a coatingmethod, or a gravure printing method. Those may include a low molecularmaterial, a middle molecular material (including an oligomer and adendrimer), or a high molecular material.

Embodiment 3

In this embodiment, a light-emitting apparatus using the light-emittingdevice described in Embodiment 1 and Embodiment 2 will be described.

In this embodiment, a light-emitting apparatus fabricated using thelight-emitting device described in Embodiment 1 and Embodiment 2 will bedescribed with reference to FIG. 2 . Note that FIG. 2(A) is a top viewillustrating the light-emitting apparatus, and FIG. 2(B) is across-sectional view taken along A-B and C-D in FIG. 2(A). Thislight-emitting apparatus includes a driver circuit portion (source linedriver circuit) 601, a pixel portion 602, and a driver circuit portion(gate line driver circuit) 603, which are for controlling light emissionof a light-emitting device and are illustrated with dotted lines.Furthermore, 604 denotes a sealing substrate, 605 denotes a sealant, andthe inside surrounded by the sealant 605 is a space 607.

Note that a lead wiring 608 is a wiring for transmitting signals to beinput to the source line driver circuit 601 and the gate line drivercircuit 603 and receiving a video signal, a clock signal, a startsignal, a reset signal, and the like from an FPC (flexible printedcircuit) 609 serving as an external input terminal. Although only theFPC is illustrated here, a printed wiring board (PWB) may be attached tothis FPC. The light-emitting apparatus in this specification includesnot only the light-emitting apparatus itself but also the apparatusprovided with the FPC or the PWB.

Next, a cross-sectional structure will be described with reference toFIG. 2(B). The driver circuit portion and the pixel portion are formedover an element substrate 610. Here, the source line driver circuit 601,which is the driver circuit portion, and one pixel of the pixel portion602 are illustrated.

The element substrate 610 may be fabricated using a substrate containingglass, quartz, an organic resin, a metal, an alloy, a semiconductor, orthe like, or a plastic substrate formed of FRP (Fiber ReinforcedPlastic), PVF (polyvinyl fluoride), polyester, acrylic, or the like.

The structure of transistors used in pixels and driver circuits is notparticularly limited. For example, an inverted staggered transistor or astaggered transistor may be used. Furthermore, top-gate transistors orbottom-gate transistors may be used. A semiconductor material used forthe transistors is not particularly limited, and for example, silicon,germanium, silicon carbide, gallium nitride, or the like can be used.Alternatively, an oxide semiconductor containing at least one of indium,gallium, and zinc, such as In—Ga—Zn-based metal oxide, may be used.

There is no particular limitation on the crystallinity of asemiconductor material used for the transistors, and any of an amorphoussemiconductor or a semiconductor having crystallinity (amicrocrystalline semiconductor, a polycrystalline semiconductor, asingle-crystal semiconductor, and a semiconductor partly includingcrystal regions) may be used. A semiconductor having crystallinity ispreferably used, in which case deterioration of the transistorcharacteristics can be suppressed.

Here, an oxide semiconductor is preferably used for semiconductordevices such as the transistors provided in the pixels and drivercircuits and transistors used for touch sensors described later, and thelike. In particular, an oxide semiconductor having a wider band gap thansilicon is preferably used. The use of an oxide semiconductor materialhaving a wider band gap than silicon can reduce the off-state current ofthe transistors.

The oxide semiconductor preferably contains at least indium (In) or zinc(Zn). Further preferably, the oxide semiconductor contains an oxiderepresented by an In-M-Zn-based oxide (M represents a metal such as Al,Ti, Ga, Ge, Y, Zr, Sn, La, Ce, or Hf).

As a semiconductor layer, it is particularly preferable to use an oxidesemiconductor film including a plurality of crystal parts whose c-axesare aligned perpendicular to a surface on which the semiconductor layeris formed or the top surface of the semiconductor layer and in which theadjacent crystal parts have no grain boundary.

The use of such a material as the semiconductor layer makes it possibleto achieve a highly reliable transistor in which a change in theelectrical characteristics is reduced.

Charge accumulated in a capacitor through a transistor including theabove-described semiconductor layer can be retained for a long timebecause of the low off-state current of the transistor. The use of sucha transistor in pixels allows a driver circuit to stop while the graylevel of an image displayed on each display region is maintained. As aresult, an electronic device with significantly reduced powerconsumption can be achieved.

For stable characteristics of the transistor or the like, a base film ispreferably provided. The base film can be formed to be a single-layer ora stacked-layer using an inorganic insulating film such as a siliconoxide film, a silicon nitride film, a silicon oxynitride film, or asilicon nitride oxide film. The base film can be formed by a sputteringmethod, a CVD (Chemical Vapor Deposition) method (e.g., a plasma CVDmethod, a thermal CVD method, or an MOCVD (Metal Organic CVD) method),an ALD (Atomic Layer Deposition) method, a coating method, a printingmethod, or the like. Note that the base film is not necessarily providedwhen not needed.

Note that an FET 623 is illustrated as a transistor formed in the drivercircuit portion 601. The driver circuit can be formed using variouscircuits such as a CMOS circuit, a PMOS circuit, and an NMOS circuit.Although a driver-integrated type in which the driver circuit is formedover the substrate is described in this embodiment, the driver circuitis not necessarily formed over the substrate and can be formed outside.

The pixel portion 602 is formed with a plurality of pixels including aswitching FET 611, a current control FET 612, and a first electrode 613electrically connected to a drain of the current control FET 612;however, without being limited thereto, a pixel portion in which threeor more FETs and a capacitor are combined may be employed.

Note that an insulator 614 is formed to cover an end portion of thefirst electrode 613. The insulator 614 can be formed using a positivephotosensitive acrylic resin film here.

In order to improve the coverage with an EL layer or the like to beformed later, the insulator 614 is formed so as to have a curved surfacewith curvature at its upper end portion or lower end portion. Forexample, in the case where positive photosensitive acrylic is used as amaterial for the insulator 614, only the upper end portion of theinsulator 614 preferably has a curved surface with a curvature radius(0.2 μm to 3 μm). As the insulator 614, either a negative photosensitiveresin or a positive photosensitive resin can be used.

An EL layer 616 and a second electrode 617 are formed over the firstelectrode 613. Here, as a material used for the first electrode 613functioning as an anode, a material with a high work function isdesirably used. For example, a single-layer film of an ITO film, anindium tin oxide film containing silicon, an indium oxide filmcontaining zinc oxide at 2 wt % to 20 wt %, a titanium nitride film, achromium film, a tungsten film, a Zn film, a Pt film, or the like, astacked layer of titanium nitride film and a film containing aluminum asits main component, a three-layer structure of a titanium nitride film,a film containing aluminum as its main component, and a titanium nitridefilm, or the like can be used. Note that the stacked-layer structureachieves low wiring resistance, a favorable ohmic contact, and afunction as an anode.

The EL layer 616 is formed by any of a variety of methods such as anevaporation method using an evaporation mask, an inkjet method, and aspin coating method. The EL layer 616 has the structure described inEmbodiment 1 and Embodiment 2. Alternatively, a material included in theEL layer 616 may be a low molecular compound or a high molecularcompound (including an oligomer or a dendrimer).

As a material used for the second electrode 617, which is formed overthe EL layer 616 and functions as a cathode, a material with a low workfunction (e.g., Al, Mg, Li, Ca, or an alloy or a compound thereof (e.g.,MgAg, MgIn, or AlLi)) is preferably used. Note that in the case wherelight generated in the EL layer 616 passes through the second electrode617, it is preferable to use, for the second electrode 617, a stackedlayer of a thin metal film and a transparent conductive film (e.g., ITO,indium oxide containing zinc oxide at 2 wt % to 20 wt %, indium tinoxide containing silicon, or zinc oxide (ZnO)).

Note that a light-emitting device is formed with the first electrode613, the EL layer 616, and the second electrode 617. The light-emittingdevice is the light-emitting device described in Embodiment 1 andEmbodiment 2. A plurality of light-emitting devices are formed in thepixel portion, and the light-emitting apparatus of this embodiment mayinclude both the light-emitting device described in Embodiment 1 andEmbodiment 2 and a light-emitting device having a different structure.

The sealing substrate 604 and the element substrate 610 are attached toeach other using the sealant 605, so that a structure is employed inwhich a light-emitting device 618 is provided in the space 607surrounded by the element substrate 610, the sealing substrate 604, andthe sealant 605. The space 607 is filled with a filler; it is filledwith an inert gas (e.g., nitrogen or argon) in some cases, and filledwith the sealant in some cases. The structure of the sealing substratein which a recessed portion is formed and a desiccant is provided ispreferable because deterioration due to the influence of moisture can beinhibited.

Note that an epoxy-based resin or glass frit is preferably used for thesealant 605. Furthermore, these materials are preferably materials thattransmit moisture or oxygen as little as possible. As the material usedfor the sealing substrate 604, in addition to a glass substrate and aquartz substrate, a plastic substrate formed of FRP (Fiber ReinforcedPlastics), PVF (polyvinyl fluoride), polyester, acrylic, or the like canbe used.

Although not illustrated in FIG. 2 , a protective film may be providedover the second electrode. The protective film may be formed using anorganic resin film or an inorganic insulating film. The protective filmmay be formed so as to cover an exposed portion of the sealant 605. Theprotective film may be provided so as to cover surfaces and sidesurfaces of the pair of substrates and exposed side surfaces of asealing layer, an insulating layer, and the like.

For the protective film, a material that is less likely transmit animpurity such as water. Thus, diffusion of an impurity such as waterfrom the outside into the inside can be effectively inhibited.

As a material included in the protective film, an oxide, a nitride, afluoride, a sulfide, a ternary compound, a metal, a polymer, or the likecan be used; for example, it is possible to use a material containingaluminum oxide, hafnium oxide, hafnium silicate, lanthanum oxide,silicon oxide, strontium titanate, tantalum oxide, titanium oxide, zincoxide, niobium oxide, zirconium oxide, tin oxide, yttrium oxide, ceriumoxide, scandium oxide, erbium oxide, vanadium oxide, indium oxide; amaterial containing aluminum nitride, hafnium nitride, silicon nitride,tantalum nitride, titanium nitride, niobium nitride, molybdenum nitride,zirconium nitride, gallium nitride; a material containing a nitridecontaining titanium and aluminum, an oxide containing titanium andaluminum, an oxide containing aluminum and zinc, a sulfide containingmanganese and zinc, a sulfide containing cerium and strontium, an oxidecontaining erbium and aluminum, an oxide containing yttrium andzirconium, or the like.

The protective film is preferably formed using a deposition method thatenables favorable step coverage. One such method is an atomic layerdeposition (ALD) method. A material that can be formed by an ALD methodis preferably used for the protective film. With the use of an ALDmethod, a dense protective film with reduced defects such as cracks andpinholes or with a uniform thickness can be formed. Furthermore, damagecaused to a process member in forming the protective film can bereduced.

By an ALD method, a uniform protective film with few defects can beformed even on a surface with a complex uneven shape or upper, side, andlower surfaces of a touch panel.

As described above, the light-emitting apparatus fabricated using thelight-emitting device described in Embodiment 1 and Embodiment 2 can beobtained.

For the light-emitting apparatus in this embodiment, the light-emittingdevice described in Embodiment 1 and Embodiment 2 is used and thus alight-emitting apparatus having favorable characteristics can beobtained. Specifically, since the light-emitting device described inEmbodiment 1 and Embodiment 2 is a light-emitting device having a longlifetime, the light-emitting apparatus can have high reliability. Sincethe light-emitting apparatus using the light-emitting device describedin Embodiment 1 and Embodiment 2 has high emission efficiency, thelight-emitting apparatus with a low power consumption can be obtained.

FIG. 3 illustrates examples of a light-emitting apparatus in which fullcolor display is achieved by formation of a light-emitting deviceexhibiting white light emission and provision of coloring layers (colorfilters) and the like. FIG. 3(A) illustrates a substrate 1001, a baseinsulating film 1002, a gate insulating film 1003, gate electrodes 1006,1007, and 1008, a first interlayer insulating film 1020, a secondinterlayer insulating film 1021, a peripheral portion 1042, a pixelportion 1040, a driver circuit portion 1041, first electrodes 1024W,1024R, 1024G, and 1024B of the light-emitting devices, a partition 1025,an EL layer 1028, a second electrode 1029 of the light-emitting devices,a sealing substrate 1031, a sealant 1032, and the like.

In FIG. 3(A), coloring layers (a red coloring layer 1034R, a greencoloring layer 1034G, and a blue coloring layer 1034B) are provided on atransparent base material 1033. A black layer (black matrix) 1035 may beadditionally provided. The transparent base material 1033 provided withthe coloring layers and the black matrix is positioned and fixed to thesubstrate 1001. Note that the coloring layers and the black matrix 1035are covered with an overcoat layer 1036. In FIG. 3(A), a light-emittinglayer from which light is emitted to the outside without passing throughthe coloring layer and light-emitting layers from which light is emittedto the outside, passing through the coloring layers of the respectivecolors are shown. Since light that does not pass through the coloringlayer is white and light that passes through the coloring layer is red,green, or blue, an image can be expressed by pixels of the four colors.

FIG. 3(B) illustrates an example in which the coloring layers (the redcoloring layer 1034R, the green coloring layer 1034G, and the bluecoloring layer 1034B) are formed between the gate insulating film 1003and the first interlayer insulating film 1020. The coloring layers maybe provided between the substrate 1001 and the sealing substrate 1031 inthis manner.

The above-described light-emitting apparatus is a light-emittingapparatus having a structure in which light is extracted to thesubstrate 1001 side where the FETs are formed (a bottom-mission type),but may be a light-emitting apparatus having a structure in which lightemission is extracted to the sealing substrate 1031 side (a top-emissiontype). FIG. 4 illustrates a cross-sectional view of a top-emissionlight-emitting apparatus. In this case, a substrate that does nottransmit light can be used as the substrate 1001. The top-emissionlight-emitting apparatus is formed in a manner similar to that of thebottom-emission light-emitting apparatus until a connection electrodewhich connects the FET and the anode of the light-emitting device isformed. Then, a third interlayer insulating film 1037 is formed to coveran electrode 1022. This insulating film may have a planarizationfunction. The third interlayer insulating film 1037 can be formed usinga material similar to that for the second interlayer insulating film orusing any other known materials.

The first electrodes 1024W, 1024R, 1024G, and 1024B of thelight-emitting elements are each an anode here, but may each be acathode. Furthermore, in the case of the top-emission light-emittingapparatus illustrated in FIG. 4 , the first electrodes are preferablyreflective electrodes. The structure of the EL layer 1028 is such astructure as described as that of the EL layer 103 in Embodiment 1 andEmbodiment 2, and an element structure with which white light emissioncan be obtained.

In the case of such a top-emission structure as in FIG. 4 , sealing canbe performed with the sealing substrate 1031 on which the coloringlayers (the red coloring layer 1034R, the green coloring layer 1034G,and the blue coloring layer 1034B) are provided. The sealing substrate1031 may be provided with the black matrix 1035 which is positionedbetween pixels. The coloring layers (the red coloring layer 1034R, thegreen coloring layer 1034G, and the blue coloring layer 1034B) and theblack matrix 1035 may be covered with the overcoat layer 1036. Note thata light-transmitting substrate is used as the sealing substrate 1031.Although an example in which full color display is performed using fourcolors of red, green, blue, and white is shown here, there is noparticular limitation and full color display may be performed using fourcolors of red, yellow, green, and blue or three colors of red, green,and blue.

In the top-emission-type light-emitting apparatus, a microcavitystructure can be favorably employed. A light-emitting device with amicrocavity structure can be obtained with the use of a reflectiveelectrode as the first electrode and a semi-transmissive andsemi-reflective electrode as the second electrode. The light-emittingdevice with a microcavity structure includes at least an EL layerbetween the reflective electrode and the semi-transmissive andsemi-reflective electrode, which includes at least a light-emittinglayer serving as a light-emitting region.

Note that the reflective electrode is a film having a visible lightreflectivity of 40% to 100%, preferably 70% to 100%, and a resistivityof 1×10⁻² Ωcm or lower. In addition, the semi-transmissive andsemi-reflective electrode is a film having a visible light reflectivityof 20% to 80%, preferably 40% to 70%, and a resistivity of 1×10⁻² Ωcm orlower.

Light emitted from the light-emitting layer included in the EL layer isreflected and resonated by the reflective electrode and thesemi-transmissive and semi-reflective electrode.

In the light-emitting device, by changing thicknesses of the transparentconductive film, the above-described composite material, thecarrier-transport material, and the like, the optical path lengthbetween the reflective electrode and the semi-transmissive andsemi-reflective electrode can be changed. Thus, light with a wavelengththat is resonated between the reflective electrode and thesemi-transmissive and semi-reflective electrode can be intensified whilelight with a wavelength that is not resonated therebetween can beattenuated.

Note that light that is reflected back by the reflective electrode(first reflected light) considerably interferes with light that directlyenters the semi-transmissive and semi-reflective electrode from thelight-emitting layer (first incident light); therefore, the optical pathlength between the reflective electrode and the light-emitting layer ispreferably adjusted to (2n−1)λ/4 (n is a natural number of 1 or largerand λ is a wavelength of light emission to be amplified). By adjustingthe optical path length, the phases of the first reflected light and thefirst incident light can be aligned with each other and the lightemitted from the light-emitting layer can be further amplified.

Note that in the above structure, the EL layer may have a structureincluding a plurality of light-emitting layers or may have a structureincluding a single light-emitting layer. The tandem light-emittingdevice described above may be combined with a plurality of EL layers;for example, a light-emitting device may have a structure in which aplurality of EL layers are provided, a charge-generation layer isprovided between the EL layers, and each EL layer includes a pluralityof light-emitting layers or a single light-emitting layer.

With the microcavity structure, emission intensity with a specificwavelength in the front direction can be increased, whereby powerconsumption can be reduced. Note that in the case of a light-emittingapparatus which displays images with subpixels of four colors, red,yellow, green, and blue, the light-emitting apparatus can have favorablecharacteristics because a microcavity structure suitable for wavelengthsof the corresponding color is employed in each subpixel, in addition tothe effect of an improvement in luminance awing to yellow lightemission.

For the light-emitting apparatus in this embodiment, the light-emittingdevice described in Embodiment 1 and Embodiment 2 is used and thus alight-emitting apparatus having favorable characteristics can beobtained. Specifically, since the light-emitting device described inEmbodiment 1 and Embodiment 2 is a light-emitting device having a longlifetime, the light-emitting apparatus can have high reliability. Sincethe light-emitting apparatus using the light-emitting device describedin Embodiment 1 and Embodiment 2 has high emission efficiency, thelight-emitting apparatus with a low power consumption can be obtained.

The active matrix light-emitting apparatus is described above, whereas apassive matrix light-emitting apparatus is described below. FIG. 5illustrates a passive matrix light-emitting apparatus fabricated usingthe present invention. Note that FIG. 5(A) is a perspective viewillustrating the light-emitting apparatus, and FIG. 5(B) is across-sectional view taken along X-Y in FIG. 5(A). In FIG. 5 , over asubstrate 951, an EL layer 955 is provided between an electrode 952 andan electrode 956. An end portion of the electrode 952 is covered with aninsulating layer 953. A partition layer 954 is provided over theinsulating layer 953. Sidewalls of the partition layer 954 are aslopesuch that the distance between one sidewall and the other sidewall isgradually narrowed toward the surface of the substrate. That is, a crosssection in the short side direction of the partition layer 954 is atrapezoidal shape, and the lower side (the side facing the samedirection as the plane direction of the insulating layer 953 andtouching the insulating layer 953) is shorter than the upper side (theside facing the same direction as the plane direction of the insulatinglayer 953, and not touching the insulating layer 953). By providing thepartition layer 954 in this manner, defects of the light-emittingelement due to static charge or the like can be prevented. Thepassive-matrix light-emitting apparatus also uses the light-emittingdevice described in Embodiment 1 and Embodiment 2; thus, thelight-emitting apparatus can have favorable reliability or low powerconsumption.

Since many minute light-emitting devices arranged in a matrix can eachbe controlled in the light-emitting apparatus described above, thelight-emitting apparatus can be suitably used as a display device fordisplaying images.

This embodiment can be freely combined with any of the otherembodiments.

Embodiment 4

In this embodiment, an example in which the light-emitting devicedescribed in Embodiment 1 and Embodiment 2 is used for a lighting devicewill be described with reference to FIG. 6 . FIG. 6(B) is a top view ofthe lighting device, and FIG. 6(A) is a cross-sectional view taken alonge-f in FIG. 6(B).

In the lighting device in this embodiment, a first electrode 401 isformed over a substrate 400 which is a support and has alight-transmitting property. The first electrode 401 corresponds to thefirst electrode 101 in Embodiment 2. In the case where light emission isextracted from the first electrode 401 side, the first electrode 401 isformed with a material having a light-transmitting property.

A pad 412 for supplying a voltage to a second electrode 404 is formedover the substrate 400.

An EL layer 403 is formed over the first electrode 401. The EL layer 403has a structure corresponding to that of the EL layer 103 in Embodiment1 and Embodiment 2, or the structure in which the light-emitting units511 and 512 are combined with the charge-generation layer 513.

Note that for these structures, the corresponding description can bereferred to.

The second electrode 404 is formed to cover the EL layer 403. The secondelectrode 404 corresponds to the second electrode 102 in Embodiment 2.In the case where light-emission is extracted from the first electrode401 side, the second electrode 404 is formed with a material having highreflectivity. The second electrode 404 is supplied with a voltage whenconnected to the pad 412.

As described above, the lighting device described in this embodimentincludes a light-emitting device including the first electrode 401, theEL layer 403, and the second electrode 404. Since the light-emittingdevice is a light-emitting device with high emission efficiency, thelighting device in this embodiment can be a lighting device with lowpower consumption.

The substrate 400 over which the light-emitting device having the abovestructure is formed is fixed to a sealing substrate 407 with sealants405 and 406 and sealing is performed, whereby the lighting device iscompleted. It is possible to use only either the sealant 405 or 406. Inaddition, the inner sealant 406 (not illustrated in FIG. 6(B)) can bemixed with a desiccant, which enables moisture to be adsorbed, resultingin improved reliability.

When parts of the pad 412 and the first electrode 401 are provided toextend to the outside of the sealants 405 and 406, those can serve asexternal input terminals. An IC chip 420 mounted with a converter or thelike may be provided over the external input terminals.

The lighting device described in this embodiment uses the light-emittingdevice described in Embodiment 1 and Embodiment 2 as an EL device; thus,the light-emitting apparatus can have favorable reliability.Furthermore, the light-emitting apparatus can have low powerconsumption.

Embodiment 5

In this embodiment, examples of electronic devices each partly includingthe light-emitting device described in Embodiment 1 and Embodiment 2 aredescribed. The light-emitting device described in Embodiment 1 andEmbodiment 2 is a light-emitting device having a favorable lifetime andfavorable reliability. As a result, the electronic devices described inthis embodiment can be electronic devices each including alight-emitting portion with favorable reliability.

Examples of electronic devices to which the light-emitting device isapplied include a television devices (also referred to as TV ortelevision receivers), monitors for computers and the like, cameras suchas digital cameras and digital video cameras, digital photo frames,mobile phones (also referred to as portable telephones or portabletelephone devices), portable game machines, portable informationterminals, audio playback devices, and large game machines such aspin-ball machines. Specific examples of these electronic devices areshown below.

FIG. 7(A) illustrates an example of a television device. In thetelevision device, a display portion 7103 is incorporated in a housing7101. Here, a structure in which the housing 7101 is supported by astand 7105 is shown. Images can be displayed on the display portion7103, and the light-emitting devices described in Embodiment 1 andEmbodiment 2 are arranged in a matrix in the display portion 7103.

The television device can be operated with an operation switch of thehousing 7101 or a separate remote controller 7110. With operation keys7109 of the remote controller 7110, channels and volume can be operatedand images displayed on the display portion 7103 can be operated.Furthermore, a structure may be employed in which the remote controller7110 is provided with a display portion 7107 for displaying data outputfrom the remote controller 7110.

Note that the television device has a structure of including a receiver,a modem, and the like. With the use of the receiver, a generaltelevision broadcast can be received, and moreover, when the televisiondevice is connected to a communication network with or without a wirevia the modem, one-way (from a sender to a receiver) or two-way (betweena sender and a receiver or between receivers) data communication can beperformed.

FIG. 7 (B1) is a computer which includes a main body 7201, a housing7202, a display portion 7203, a keyboard 7204, an external connectionport 7205, a pointing device 7206, and the like. Note that this computeris fabricated using the light-emitting devices described in Embodiment 1and Embodiment 2 arranged in a matrix in the display portion 7203. Thecomputer in FIG. 7 (B1) may be such a mode as illustrated in FIG. 7(B2). The computer in FIG. 7 (B2) is provided with a second displayportion 7210 instead of the keyboard 7204 and the pointing device 7206.The second display portion 7210 is of a touch-panel type, and input canbe performed by operating display for input displayed on the seconddisplay portion 7210 with a finger or a dedicated pen. The seconddisplay portion 7210 can also display images other than the display forinput. The display portion 7203 may also be a touch panel. Connectingthe two screens with a hinge can prevent troubles such as a crack in ordamage to the screens caused when the computer is stored or carried.

FIG. 7(C) illustrates an example of a portable terminal. A mobile phoneincludes operation buttons 7403, an external connection port 7404, aspeaker 7405, a microphone 7406, and the like in addition to a displayportion 7402 incorporated in a housing 7401. Note that a mobile phone7400 includes the display portion 7402 which is fabricated by arrangingthe light-emitting devices described in Embodiment 1 and Embodiment 2 ina matrix.

The portable terminal illustrated in FIG. 7(C) may have a structure inwhich information can be input by touching the display portion 7402 witha finger or the like. In this case, operations such as making a call andcreating an e-mail can be performed by touching the display portion 7402with a finger or the like.

The display portion 7402 has mainly three screen modes. The first one isa display mode mainly for displaying images, and the second one is aninput mode mainly for inputting data such as text. The third one is adisplay+input mode in which two modes of the display mode and the inputmode are combined.

For example, in the case of making a call or creating an e-mail, a textinput mode mainly for inputting text is selected for the display portion7402 so that an operation of inputting text displayed on the screen maybe performed. In this case, it is preferable to display a keyboard ornumber buttons on almost the entire screen of the display portion 7402.

When a sensing device including a sensor for sensing inclination, suchas a gyroscope sensor or an acceleration sensor, is provided inside theportable terminal, screen display of the display portion 7402 can beautomatically changed by determining the orientation of the portableterminal (vertically or horizontally).

The screen modes are changed by touching the display portion 7402 oroperating the operation buttons 7403 of the housing 7401. Alternatively,the screen modes can be changed depending on the kind of image displayedon the display portion 7402. For example, when a signal of an imagedisplayed on the display portion is moving image data, the screen modeis changed to the display mode, and when the signal is text data, thescreen mode is changed to the input mode.

Moreover, in the input mode, when input by the touch operation of thedisplay portion 7402 is not performed for a certain period while asignal sensed by an optical sensor in the display portion 7402 issensed, the screen mode may be controlled so as to be changed from theinput mode to the display mode.

The display portion 7402 can also function as an image sensor. Forexample, an image of a palm print, a fingerprint, or the like is takenwhen the display portion 7402 is touched with the palm or the finger,whereby personal authentication can be performed. Furthermore, by usinga backlight which emits near-infrared light or a sensing light sourcewhich emits near-infrared light in the display portion, an image of afinger vein, a palm vein, or the like can be taken.

Note that the structures described in this embodiment can be combinedwith the structures described in any of Embodiment 1 to Embodiment 4 asappropriate.

As described above, the application range of the light-emittingapparatus including the light-emitting device described in Embodiment 1and Embodiment 2 is wide so that this light-emitting apparatus can beapplied to electronic devices in a variety of fields. With the use ofthe light-emitting device described in Embodiment 1 and Embodiment 2, anelectronic device with high reliability can be obtained.

FIG. 8(A) is a schematic view illustrating an example of a cleaningrobot.

A cleaning robot 5100 includes a display 5101 placed on its top surface,a plurality of cameras 5102 placed on its side surface, a brush 5103,and operation buttons 5104. Although not illustrated, the bottom surfaceof the cleaning robot 5100 is provided with a tire, an inlet, and thelike. Furthermore, the cleaning robot 5100 includes various sensors suchas an infrared sensor, an ultrasonic sensor, an acceleration sensor, apiezoelectric sensor, an optical sensor, and a gyroscope sensor. Inaddition, the cleaning robot 5100 has a wireless communication means.

The cleaning robot 5100 is self-propelled, detects dust 5120, and sucksup the dust through the inlet provided on the bottom surface.

The cleaning robot 5100 can judge whether there is an obstacle such as awall, furniture, or a step by analyzing images taken by the cameras5102. When an object that is likely to be caught in the brush 5103, suchas a wire, is detected by image analysis, the rotation of the brush 5103can be stopped.

The display 5101 can display the remaining capacity of a battery, theamount of vacuumed dust, and the like. The display 5101 may display apath on which the cleaning robot 5100 has run. The display 5101 may be atouch panel, and the operation buttons 5104 may be provided on thedisplay 5101.

The cleaning robot 5100 can communicate with a portable electronicdevice 5140 such as a smartphone. The portable electronic device 5140can display images taken by the cameras 5102. Accordingly, an owner ofthe cleaning robot 5100 can monitor the room even from the outside. Thedisplay on the display 5101 can be checked by the portable electronicdevice 5140 such as a smartphone.

The light-emitting apparatus of one embodiment of the present inventioncan be used for the display 5101.

A robot 2100 illustrated in FIG. 8(B) includes an arithmetic device2110, an illuminance sensor 2101, a microphone 2102, an upper camera2103, a speaker 2104, a display 2105, a lower camera 2106, an obstaclesensor 2107, and a moving mechanism 2108.

The microphone 2102 has a function of detecting a speaking voice of auser, an environmental sound, and the like. The speaker 2104 also has afunction of outputting sound. The robot 2100 can communicate with a userusing the microphone 2102 and the speaker 2104.

The display 2105 has a function of displaying various kinds ofinformation. The robot 2100 can display information desired by a user onthe display 2105. The display 2105 may be provided with a touch panel.Moreover, the display 2105 may be a detachable information terminal, inwhich case charging and data communication can be performed when thedisplay 2105 is set at the home position of the robot 2100.

The upper camera 2103 and the lower camera 2106 each have a function oftaking an image of the surroundings of the robot 2100. The obstaclesensor 2107 can detect the presence of an obstacle in the directionwhere the robot 2100 advances with the moving mechanism 2108. The robot2100 can move safely by recognizing the surroundings with the uppercamera 2103, the lower camera 2106, and the obstacle sensor 2107. Thelight-emitting apparatus of one embodiment of the present invention canbe used for the display 2105.

FIG. 8(C) shows an example of a goggle-type display. The goggle-typedisplay includes, for example, a housing 5000, a display portion 5001, aspeaker 5003, an LED lamp 5004, an operation keys 5005 (including apower switch or an operation switch), a connection terminal 5006, asensor 5007 (a sensor having a function of measuring force,displacement, position, speed, acceleration, angular velocity,rotational frequency, distance, light, liquid, magnetism, temperature,chemical substance, sound, time, hardness, electric field, current,voltage, power, radiation, flow rate, humidity, gradient, oscillation,odor, or infrared ray), a microphone 5008, a second display portion5002, a support 5012, and an earphone 5013.

The light-emitting apparatus of one embodiment of the present inventioncan be used for the display portion 5001 and the second display portion5002.

FIG. 9 illustrates an example in which the light-emitting devicedescribed in Embodiment 1 and Embodiment 2 is used for a table lampwhich is a lighting device. The table lamp illustrated in FIG. 9includes a housing 2001 and a light source 2002, and the lighting devicedescribed in Embodiment 3 may be used for the light source 2002.

FIG. 10 illustrates an example in which the light-emitting devicedescribed in Embodiment 1 and Embodiment 2 is used for an indoorlighting device 3001. Since the light-emitting device described inEmbodiment 1 and Embodiment 2 is a light-emitting device having highreliability, the lighting device can have high reliability. Furthermore,the light-emitting device described in Embodiment 1 and Embodiment 2 canhave a larger area, and thus can be used for a large-area lightingdevice. Furthermore, the light-emitting device described in Embodiment 1and Embodiment 2 is thin, and thus can be used for a lighting devicehaving a reduced thickness.

The light-emitting device described in Embodiment 1 and Embodiment 2 canalso be incorporated in an automobile windshield or an automobiledashboard. FIG. 11 illustrates one mode in which the light-emittingdevice described in Embodiment 1 and Embodiment 2 is used for awindshield and a dashboard of an automobile. A display region 5200 to adisplay region 5203 are each a display region provided using thelight-emitting device described in Embodiment 1 and Embodiment 2.

The display region 5200 and the display region 5201 are display devicesprovided in the automobile windshield, in which the light-emittingdevices described in Embodiment 1 and Embodiment 2 are incorporated.When the light-emitting devices described in Embodiment 1 and Embodiment2 are fabricated using electrodes having light-transmitting propertiesas a first electrode and a second electrode, what is called see-throughdisplay devices, through which the opposite side can be seen, can beobtained. See-through display devices can be provided without hinderingthe vision even when being provided in the automobile windshield. Notethat in the case where a driving transistor or the like is provided, atransistor having a light-transmitting property, such as an organictransistor using an organic semiconductor material or a transistor usingan oxide semiconductor, is preferably used.

The display region 5202 is a display device provided in a pillarportion, in which the light-emitting devices described in Embodiment 1and Embodiment 2 are incorporated. The display region 5202 cancompensate for the view hindered by the pillar by displaying an imagetaken by an imaging means provided on the car body. Similarly, thedisplay region 5203 provided in the dashboard portion can compensate forthe view hindered by the car body by displaying an image taken by animaging means provided on the outside of the automobile. Thus, blindareas can be compensated for and the safety can be enhanced. Showing animage so as to compensate for the area that cannot be seen makes itpossible to confirm safety more naturally and comfortably.

The display region 5203 can provide a variety of kinds of information bydisplaying navigation data, a speedometer, a tachometer, a mileage, afuel meter, a gearshift state, air-condition setting, and the like. Thecontent or layout of the display can be changed freely in accordancewith the preference of a user. Note that such information can also beprovided on the display region 5200 to the display region 5202. Thedisplay region 5200 to the display region 5203 can also be used aslighting devices.

FIGS. 12(A) and 12(B) illustrate a foldable portable informationterminal 5150. The foldable portable information terminal 5150 includesa housing 5151, a display region 5152, and a bend portion 5153. FIG.12(A) illustrates the portable information terminal 5150 that is opened.FIG. 12(B) illustrates the portable information terminal 5150 that isfolded. The portable information terminal 5150 is compact in size andhas excellent portability when folded, despite its large display region5152.

The display region 5152 can be folded in half with the bend portion5153. The bend portion 5153 includes a flexible member and a pluralityof supporting members, and when the display region is folded, theflexible member expands and the bend portion 5153 has a radius ofcurvature of 2 mm or more, preferably 3 mm or more.

Note that the display region 5152 may be a touch panel (an input/outputdevice) including a touch sensor (an input device). The light-emittingapparatus of one embodiment of the present invention can be used for thedisplay region 5152.

FIGS. 13(A) to 13(C) illustrate a foldable portable information terminal9310. FIG. 13(A) illustrates the portable information terminal 9310 thatis opened. FIG. 13(B) illustrates the portable information terminal 9310which is in the state of being changed from one of an opened state and afolded state to the other. FIG. 13(C) illustrates the portableinformation terminal 9310 that is folded. The portable informationterminal 9310 is excellent in portability when folded, and is excellentin display browsability when opened because of a seamless large displayregion.

A display panel 9311 is supported by three housings 9315 joined togetherby hinges 9313. Note that the display panel 9311 may be a touch panel(an input/output device) including a touch sensor (an input device). Byfolding the display panel 9311 at the hinges 9313 between two housings9315, the portable information terminal 9310 can be reversibly changedin shape from the opened state to the folded state. A light-emittingapparatus of one embodiment of the present invention can be used for thedisplay panel 9311. A display region 9312 in the display panel 9311 is adisplay region that is positioned at a side surface of the portableinformation terminal 9310 which is folded. On the display region 9312,information icons, file shortcuts of frequently used applications orprograms, and the like can be displayed, and confirmation of informationand start of an application can be smoothly performed.

EXAMPLE Device Example 1

In this example, a light-emitting device 1 of one embodiment of thepresent invention and a comparative light-emitting device 1 will bedescribed. The structural formulae of organic compounds used in thelight-emitting device 1 and the comparative light-emitting device 1 areshown below.

(Fabricating Method of Light-Emitting Device 1)

First, a film of indium tin oxide containing silicon oxide (ITSO) wasformed over a glass substrate by a sputtering method, so that the firstelectrode 101 was formed. Note that the thickness was 70 nm and the areaof the electrode was 2 mm×2 mm.

Next, in pretreatment for forming the light-emitting device over thesubstrate, the surface of the substrate was washed with water and bakedat 200° C. for one hour, and then UV ozone treatment was performed for370 seconds.

After that, the substrate was transferred into a vacuum evaporationapparatus in which the pressure was reduced to about 10⁻⁴ Pa, vacuumbaking at 170° C. for 30 minutes was performed in a heating chamber inthe vacuum evaporation apparatus, and then the substrate was naturallycooled down for about 30 minutes.

Next, the substrate provided with the first electrode 101 was fixed to asubstrate holder provided in the vacuum evaporation apparatus such thatthe side on which the first electrode 101 was formed faced downward, andthen N,N-bis(4-biphenyl)-6-phenylbenzo[b]naphtho[1,2-d]furan-8-amine(abbreviation: BBABnf) represented by the structural formula (i) andNDP-9 (produced by Analysis Atelier Corporation, material serial No.1S20170124) were deposited by co-evaporation to a thickness of 10 nm onthe first electrode 101 at a weight ratio of 1:0.1 (=BBABnf:NDP-9) by anevaporation method using resistance heating, whereby the hole-injectionlayer 111 was formed.

Subsequently, over the hole-injection layer 111, BBABnf was deposited asa first hole-transport layer 112-1 by evaporation to a thickness of 20nm, and then 3,3′-(naphthalene-1,4-diyl)bis(9-phenyl-9H-carbazole)(abbreviation: PCzN2) represented by the structural formula (ii) wasdeposited as a second hole-transport layer 112-2 by evaporation to athickness of 10 nm, whereby the hole-transport layer 112 was formed.

Then, 7-[4-(10-phenyl-9-anthryl)phenyl]-7H-dibenzo[c,g]carbazole(abbreviation: cgDBCzPA) represented by the structural formula (iii) andN,N′-(pyrene-1,6-diyl)bis[(6,N-diphenylbenzo[b]naphtho[1,2-d]furan)-8-amine](abbreviation: 1,6BnfAPrn-03) represented by the structural formula (iv)were deposited to a thickness of 25 nm by co-evaporation at a weightratio of 1:0.03 (=cgDBCzPA:1,6BnfAPrn-03), whereby the light-emittinglayer 113 was formed.

After that, over the light-emitting layer 113, cgDBCzPA was deposited byevaporation to a thickness of 15 nm, and then2,9-bis(naphthalen-2-yl)-4,7-diphenyl-1,10-phenanthroline (abbreviation:NBPhen) represented by the structural formula (v) was deposited byevaporation to a thickness of 10 nm, whereby the electron-transportlayer 114 was formed.

After the formation of the electron-transport layer 114, lithiumfluoride (LiF) was deposited by evaporation to a thickness of 1 nm toform the electron-injection layer 115, and then aluminum was depositedby evaporation to a thickness of 200 nm to form the second electrode102, whereby the light-emitting device 1 of this example was fabricated.

(Fabricating Method of Comparative Light-Emitting Device 1)

The comparative light-emitting device 1 was fabricated in a mannersimilar to that of the light-emitting device 1 except that PCzN2 used inthe second hole-transport layer 112-2 of the light-emitting device 1 wasreplaced with 3-[4-(9-phenanthryl)-phenyl]-9-phenyl-9H-carbazole(abbreviation: PCPPn) represented by the structural formula (vi).

The device structures of the light-emitting device 1 and the comparativelight-emitting device 1 are listed in the following table.

TABLE 1 Hole- Hole-transport Light- Electron- injection layer emittingElectron-transport injection layer 1 2 layer layer layer 10 nm 20 nm 10nm 25 nm 15 nm 10 nm 1 nm Light-emitting BBABnf: BBABnf PCzN2 cgDBCzPA:cgDBCzPA NBPhen LiF device 1 NDP-9 1,6BnfAPrn-03 Comparative (1:0.1)PCPPn (1:0.03) light-emitting device 1

The light-emitting device 1 and the comparative light-emitting device 1were each subjected to sealing with a glass substrate (a sealant wasapplied to surround the device, followed by UV treatment and one-hourheat treatment at 80° C. at the time of sealing) in a glove box in anitrogen atmosphere so that the light-emitting device is not exposed tothe air, and then initial characteristics and reliabilities of theselight-emitting devices were measured. Note that the measurement wasperformed at room temperature.

Luminance-current density characteristics of the light-emitting device 1and the comparative light-emitting device 1 are shown in FIG. 14 ,current efficiency-luminance characteristics thereof are shown in FIG.15 , luminance-voltage characteristics thereof are shown in FIG. 16 ,current-voltage characteristics thereof are shown in FIG. 17 , externalquantum efficiency-luminance characteristics thereof are shown in FIG.18 , and emission spectra thereof are shown in FIG. 19 . In addition,Table 2 shows the main characteristics of the light-emitting devices ataround 1000 cd/m².

TABLE 2 External Current Current quantum Voltage Current density Chroma-Chroma- efficiency efficiency (V) (mA) (mA/cm²) ticity x ticity y (cd/A)(%) Light-emitting 3.0 0.28 7.1 0.14 0.12 10.4 10.5 device 1 Comparative3.2 0.36 9.0 0.14 0.13 11.1 10.9 light-emitting device 1

It was found from FIG. 14 to FIG. 19 and Table 2 that the light-emittingdevice 1, which is one embodiment of the present invention, was afavorable blue light-emitting device in which the driving voltage waslow and the characteristics such as the emission efficiency wereequivalent to those of the comparative light-emitting device 1.

FIG. 20 is a graph showing a change in luminance over driving time at acurrent density of 50 mA/cm². As shown in FIG. 20 , the light-emittingdevice 1, which is a light-emitting device of one embodiment of thepresent invention, was found to be a light-emitting device withfavorable lifetime with a small reduction in luminance over theaccumulated driving time.

Device Example 2

In this example, a light-emitting device 2 of one embodiment of thepresent invention and a comparative light-emitting device 2 will bedescribed. The structural formulae of organic compounds used in thelight-emitting device 2 and the comparative light-emitting device 2 areshown below.

(Fabricating Method of Light-Emitting Device 2)

First, a film of indium tin oxide containing silicon oxide (ITSO) wasformed over a glass substrate by a sputtering method, so that the firstelectrode 101 was formed. Note that the thickness was 70 nm and the areaof the electrode was 2 mm×2 mm.

Next, in pretreatment for forming the light-emitting device over thesubstrate, the surface of the substrate was washed with water and bakedat 200° C. for one hour, and then UV ozone treatment was performed for370 seconds.

After that, the substrate was transferred into a vacuum evaporationapparatus in which the pressure was reduced to about 10⁻⁴ Pa, vacuumbaking at 170° C. for 30 minutes was performed in a heating chamber inthe vacuum evaporation apparatus, and then the substrate was naturallycooled down for about 30 minutes.

Next, the substrate provided with the first electrode 101 was fixed to asubstrate holder provided in the vacuum evaporation apparatus such thatthe side on which the first electrode 101 was formed faced downward, andthen N,N-bis(4-biphenyl)-6-phenylbenzo[b]naphtho[1,2-d]furan-8-amine(abbreviation: BBABnf) represented by Structural formula (i) shown aboveand NDP-9 (produced by Analysis Atelier Corporation, material serial No.1S20170124) were deposited by co-evaporation to a thickness of 10 nm onthe first electrode 101 at a weight ratio of 1:0.1 (=BBABnf:NDP-9) by anevaporation method using resistance heating, whereby the hole-injectionlayer 111 was formed.

Subsequently, over the hole-injection layer 111,3,3′-(naphthalene-1,4-diyl)bis(9-phenyl-9H-carbazole) (abbreviation:PCzN2) represented by the structural formula (ii) was deposited byevaporation to a thickness of 30 nm, whereby the hole-transport layer112 was formed.

Then, 7-[4-(10-phenyl-9-anthryl)phenyl]-7H-dibenzo[c,g]carbazole(abbreviation: cgDBCzPA) represented by the structural formula (iii) andN,N′-(pyrene-1,6-diyl)bis[(6,N-diphenylbenzo[b]naphtho[1,2-d]furan)-8-amine](abbreviation: 1,6BnfAPrn-03) represented by the structural formula (iv)were deposited to a thickness of 25 nm by co-evaporation at a weightratio of 1:0.03 (=cgDBCzPA:1,6BnfAPrn-03), whereby the light-emittinglayer 113 was formed.

After that, over the light-emitting layer 113, cgDBCzPA was deposited byevaporation to a thickness of 15 nm, and then2,9-bis(naphthalen-2-yl)-4,7-diphenyl-1,10-phenanthroline (abbreviation:NBPhen) represented by the structural formula (v) was deposited byevaporation to a thickness of 10 nm, whereby the electron-transportlayer 114 was formed.

After the formation of the electron-transport layer 114, lithiumfluoride (LiF) was deposited by evaporation to a thickness of 1 nm toform the electron-injection layer 115, and then aluminum was depositedby evaporation to a thickness of 200 nm to form the second electrode102, whereby the light-emitting device 2 of this example was fabricated.

(Fabricating Method of Comparative Light-Emitting Device 2)

The comparative light-emitting device 2 was fabricated in a mannersimilar to that of the light-emitting device 2 except that PCzN2 used inthe hole-transport layer 112 of the light-emitting device 2 was replacedwith 3-[4-(9-phenanthryl)-phenyl]-9-phenyl-9H-carbazole (abbreviation:PCPPn) represented by the structural formula (vi).

The device structures of the light-emitting device 2 and the comparativelight-emitting device 2 are listed in the following table.

TABLE 3 Hole- Hole- Light- Electron- Electron- injection transportemitting transport injection layer layer layer layer layer 10 nm 30 nm25 nm 15 nm 10 nm 1 nm Light-emitting BBABnf: PCzN2 cgDBCzPA: cgDBCzPANBPhen LiF device 2 NDP-9 1,6BnfAPrn-03 Comparative (1:0.1) PCPPn(1:0.03) light-emitting device 2

The light-emitting device 2 and the comparative light-emitting device 2were each subjected to sealing with a glass substrate (a sealant wasapplied to surround the device, followed by UV treatment and one-hourheat treatment at 80° C. at the time of sealing) in a glove box in anitrogen atmosphere so that the light-emitting device is not exposed tothe air, and then initial characteristics and reliabilities of theselight-emitting devices were measured. Note that the measurement wasperformed at room temperature.

Luminance-current density characteristics of the light-emitting device 2and the comparative light-emitting device 2 are shown in FIG. 21 ,current efficiency-luminance characteristics thereof are shown in FIG.22 , luminance-voltage characteristics thereof are shown in FIG. 23 ,current-voltage characteristics thereof are shown in FIG. 24 , externalquantum efficiency-luminance characteristics thereof are shown in FIG.25 , and emission spectra thereof are shown in FIG. 26 . In addition,Table 4 shows the main characteristics of the light-emitting devices ataround 1000 cd/m².

TABLE 4 External Current Current quantum Voltage Current density Chroma-Chroma- efficiency efficiency (V) (mA) (mA/cm²) ticity x ticity y (cd/A)(%) Light-emitting 3.1 0.37 9.1 0.14 0.11 10.1 11.0 device 2 Comparative3.3 0.43 10.6 0.14 0.12 10.9 11.2 light-emitting device 2

It was found from FIG. 21 to FIG. 25 and Table 4 that the light-emittingdevice 2, which is one embodiment of the present invention, was afavorable blue light-emitting device in which the driving voltage waslow and the characteristics such as the emission efficiency wereequivalent to those of the comparative light-emitting device 2.

FIG. 27 is a graph showing a change in luminance over driving time at acurrent density of 50 mA/cm². As shown in FIG. 27 , the light-emittingdevice 2, which is a light-emitting device of one embodiment of thepresent invention, was found to be a light-emitting device withfavorable lifetime with a small reduction in luminance over theaccumulated driving time.

Device Example 3

In this example, a light-emitting device 3 of one embodiment of thepresent invention and a comparative light-emitting device 3 will bedescribed. The structural formulae of organic compounds used in thelight-emitting device 3 and the comparative light-emitting device 3 areshown below.

(Fabricating Method of Light-Emitting Device 3)

First, a film of indium tin oxide containing silicon oxide (ITSO) wasformed over a glass substrate by a sputtering method, so that the firstelectrode 101 was formed. Note that the thickness was 70 nm and the areaof the electrode was 2 mm×2 mm.

Next, in pretreatment for forming the light-emitting device over thesubstrate, the surface of the substrate was washed with water and bakedat 200° C. for one hour, and then UV ozone treatment was performed for370 seconds.

After that, the substrate was transferred into a vacuum evaporationapparatus in which the pressure was reduced to about 10⁻⁴ Pa, vacuumbaking at 170° C. for 30 minutes was performed in a heating chamber inthe vacuum evaporation apparatus, and then the substrate was naturallycooled down for about 30 minutes.

Next, the substrate provided with the first electrode 101 was fixed to asubstrate holder provided in the vacuum evaporation apparatus such thatthe side on which the first electrode 101 was formed faced downward, andthen N,N-bis(4-biphenyl)-6-phenylbenzo[b]naphtho[1,2-d]furan-8-amine(abbreviation: BBABnf) represented by Structural formula (i) shown aboveand NDP-9 (produced by Analysis Atelier Corporation, material serial No.1S20170124) were deposited by co-evaporation to a thickness of 10 nm onthe first electrode 101 at a weight ratio of 1:0.1 (=BBABnf:NDP-9) by anevaporation method using resistance heating, whereby the hole-injectionlayer 111 was formed.

Subsequently, over the hole-injection layer 111, BBABnf was deposited asthe first hole-transport layer 112-1 by evaporation to a thickness of 20nm, and then 3,3′-(naphthalene-1,4-diyl)bis(9-phenyl-9H-carbazole)(abbreviation: PCzN2) represented by the structural formula (ii) wasdeposited as the second hole-transport layer 112-2 by evaporation to athickness of 10 nm, whereby the hole-transport layer 112 was formed.

Then, 7-[4-(10-phenyl-9-anthryl)phenyl]-7H-dibenzo[c,g]carbazole(abbreviation: cgDBCzPA) represented by the structural formula (iii) andN,N′-(pyrene-1,6-diyl)bis[(6,N-diphenylbenzo[b]naphtho[1,2-d]furan)-8-amine](abbreviation: 1,6BnfAPrn-03) represented by the structural formula (iv)were deposited to a thickness of 25 nm by co-evaporation at a weightratio of 1:0.03 (=cgDBCzPA:1,6BnfAPrn-03), whereby the light-emittinglayer 113 was formed.

Then, over the light-emitting layer 113,2-{4-[9,10-di(naphthalen-2-yl)-2-anthryl]-1-phenyl-1H-benzoimidazole(abbreviation: ZADN) represented by the structural formula (vii) and8-hydroxyquinolinolato-lithium (abbreviation: Liq) represented by thestructural formula (viii) were deposited by evaporation to a thicknessof 25 nm at a weight ratio of 1:1 (=ZADN:Liq), whereby theelectron-transport layer 114 was formed.

After the formation of the electron-transport layer 114, Liq wasdeposited by evaporation to a thickness of 1 nm to form theelectron-injection layer 115, and then aluminum was deposited byevaporation to a thickness of 200 nm to form the second electrode 102,whereby the light-emitting device 3 of this example was fabricated.

(Fabricating Method of Comparative Light-Emitting Device 3)

The comparative light-emitting device 3 was fabricated in a mannersimilar to that of the light-emitting device 3 except that PCzN2 used inthe hole-transport layer 112 of the light-emitting device 3 was replacedwith 3-[4-(9-phenanthryl)-phenyl]-9-phenyl-9H-carbazole (abbreviation:PCPPn) represented by the structural formula (vi).

The device structures of the light-emitting device 3 and the comparativelight-emitting device 3 are listed in the following table.

TABLE 5 Hole- Hole-transport Light- Electron- Electron- injection layeremitting transport injection layer 1 2 layer layer layer 10 nm 20 nm 10nm 25 nm 25 nm 1 nm Light-emitting BBABnf: BBABnf PCzN2 cgDBCzPA:ZADN:Liq Liq device 3 NDP-9 1,6BnfAPrn-03 (1:1) Comparative (1:0.1)PCPPn (1:0.03) light-emitting device 3

The light-emitting device 3 and the comparative light-emitting device 3were each subjected to sealing with a glass substrate (a sealant wasapplied to surround the device, followed by UV treatment and one-hourheat treatment at 80° C. at the time of sealing) in a glove box in anitrogen atmosphere so that the light-emitting device is not exposed tothe air, and then initial characteristics and reliabilities of theselight-emitting devices were measured. Note that the measurement wasperformed at room temperature.

Luminance-current density characteristics of the light-emitting device 3and the comparative light-emitting device 3 are shown in FIG. 28 ,current efficiency-luminance characteristics thereof are shown in FIG.29 , luminance-voltage characteristics thereof are shown in FIG. 30 ,current-voltage characteristics thereof are shown in FIG. 31 , externalquantum efficiency-luminance characteristics thereof are shown in FIG.32 , and emission spectra thereof are shown in FIG. 33 . In addition,Table 6 shows the main characteristics of the light-emitting devices ataround 1000 cd/m².

TABLE 6 External Current Current quantum Voltage Current density Chroma-Chroma- efficiency efficiency (V) (mA) (mA/cm²) ticity x ticity y (cd/A)(%) Light-emitting 3.6 0.43 10.7 0.14 0.13 9.5 9.4 device 3 Comparative3.6 0.40 10.0 0.14 0.13 10.5 10.0 light-emitting device 3

It was found from FIG. 28 to FIG. 32 and Table 6 that the light-emittingdevice 3, which is one embodiment of the present invention, was afavorable blue light-emitting device in which the driving voltage waslow and the characteristics such as the emission efficiency wereequivalent to those of the comparative light-emitting device 3.

FIG. 34 is a graph showing a change in luminance over driving time at acurrent density of 50 mA/cm². As shown in FIG. 34 , the light-emittingdevice 3, which is a light-emitting device of one embodiment of thepresent invention, kept 97% or more of the initial luminance even when300 hours have passed, and thus was found to be a light-emitting devicewith a favorable lifetime and an extremely small reduction in theluminance over the accumulated driving time.

Device Example 4

In this example, a light-emitting device 4 of one embodiment of thepresent invention and a comparative light-emitting device 4 will bedescribed. The structural formulae of organic compounds used in thelight-emitting device 4 and the comparative light-emitting device 4 areshown below.

(Fabricating Method of Light-Emitting Device 4)

First, a film of indium tin oxide containing silicon oxide (ITSO) wasformed over a glass substrate by a sputtering method, so that the firstelectrode 101 was formed. Note that the thickness was 70 nm and the areaof the electrode was 2 mm×2 mm.

Next, in pretreatment for forming the light-emitting device over thesubstrate, the surface of the substrate was washed with water and bakedat 200° C. for one hour, and then UV ozone treatment was performed for370 seconds.

After that, the substrate was transferred into a vacuum evaporationapparatus in which the pressure was reduced to about 10⁻⁴ Pa, vacuumbaking at 170° C. for 30 minutes was performed in a heating chamber inthe vacuum evaporation apparatus, and then the substrate was naturallycooled down for about 30 minutes.

Next, the substrate provided with the first electrode 101 was fixed to asubstrate holder provided in the vacuum evaporation apparatus such thatthe side on which the first electrode 101 was formed faced downward, andthen N,N-bis(4-biphenyl)-6-phenylbenzo[b]naphtho[1,2-d]furan-8-amine(abbreviation: BBABnf) represented by Structural formula (i) shown aboveand NDP-9 (produced by Analysis Atelier Corporation, material serial No.1S20170124) were deposited by co-evaporation to a thickness of 10 nm onthe first electrode 101 at a weight ratio of 1:0.1 (=BBABnf:NDP-9) by anevaporation method using resistance heating, whereby the hole-injectionlayer 111 was formed.

Subsequently, over the hole-injection layer 111, BBABnf was deposited asthe first hole-transport layer 112-1 by evaporation to a thickness of 20nm, and then 3,3′-(naphthalene-1,4-diyl)bis(9-phenyl-9H-carbazole)(abbreviation: PCzN2) represented by the structural formula (ii) wasdeposited as the second hole-transport layer 112-2 by evaporation to athickness of 10 nm, whereby the hole-transport layer 112 was formed.

Then, 7-[4-(10-phenyl-9-anthryl)phenyl]-7H-dibenzo[c,g]carbazole(abbreviation: cgDBCzPA) represented by the structural formula (iii) andN,N′-(pyrene-1,6-diyl)bis[(6,N-diphenylbenzo[b]naphtho[1,2-d]furan)-8-amine](abbreviation: 1,6BnfAPrn-03) represented by the structural formula (iv)were deposited to a thickness of 25 nm by co-evaporation at a weightratio of 1:0.03 (=cgDBCzPA:1,6BnfAPrn-03), whereby the light-emittinglayer 113 was formed.

After that, over the light-emitting layer 113, cgDBCzPA was deposited byevaporation to a thickness of 15 nm, and then2,9-bis(naphthalen-2-yl)-4,7-diphenyl-1,10-phenanthroline (abbreviation:NBPhen) represented by the structural formula (v) was deposited byevaporation to a thickness of 10 nm, whereby the electron-transportlayer 114 was formed.

After the formation of the electron-transport layer 114, lithiumfluoride (LiF) was deposited by evaporation to a thickness of 1 nm toform the electron-injection layer 115, and then aluminum was depositedby evaporation to a thickness of 200 nm to form the second electrode102, whereby the light-emitting device 4 of this example was fabricated.

(Fabricating Method of Comparative Light-Emitting Device 4)

The comparative light-emitting device 4 was fabricated in a mannersimilar to that of the light-emitting device 4 except that BBABnf usedin the hole-injection layer 111 and the first hole-transport layer 112-1of the light-emitting device 4 was replaced withN-(1,1′-biphenyl-4-yl)-9,9-dimethyl-N-[4-(9-phenyl-9H-carbazol-3-yl)phenyl]-9H-fluoren-2-amine(abbreviation: PCBBiF) represented by the structural formula (ix).

The device structures of the light-emitting device 4 and the comparativelight-emitting device 4 are listed in the following table.

TABLE 7 Hole- Hole-transport Light- Electron- injection layer emittingElectron-transport injection layer 1 2 layer layer layer 10 nm 20 nm 10nm 25 nm 15 nm 10 nm 1 nm Light-emitting BBABnf: BBABnf PCzN2 cgDBCzPA:cgDBCzPA NBPhen LiF device 4 NDP-9 1,6BnfAPrn-03 (1:0.1) (1:0.03)Comparative PCBBiF: PCBBiF light-emitting NDP-9 device 4 (1:0.1)

The light-emitting device 4 and the comparative light-emitting device 4were each subjected to sealing with a glass substrate (a sealant wasapplied to surround the device, followed by UV treatment and one-hourheat treatment at 80° C. at the time of sealing) in a glove box in anitrogen atmosphere so that the light-emitting device is not exposed tothe air, and then initial characteristics and reliabilities of theselight-emitting devices were measured. Note that the measurement wasperformed at room temperature.

Luminance-current density characteristics of the light-emitting device 4and the comparative light-emitting device 4 are shown in FIG. 35 ,current efficiency-luminance characteristics thereof are shown in FIG.36 , luminance-voltage characteristics thereof are shown in FIG. 37 ,current-voltage characteristics thereof are shown in FIG. 38 , externalquantum efficiency-luminance characteristics thereof are shown in FIG.39 , and emission spectra thereof are shown in FIG. 40 . In addition,Table 8 shows the main characteristics of the light-emitting devices ataround 1000 cd/m².

TABLE 8 External Current Current quantum Voltage Current density Chroma-Chroma- efficiency efficiency (V) (mA) (mA/cm²) ticity x ticity y (cd/A)(%) Light-emitting 3.0 0.28 7.1 0.14 0.12 10.4 10.5 device 4 Comparative3.6 0.41 10.2 0.14 0.13 7.9 7.7 light-emitting device 4

According to FIG. 35 to FIG. 39 and Table 8, since the light-emittingdevice 4, which is one embodiment of the present invention, uses thehole-transport material that has a deeper HOMO level than that of thecomparative light-emitting device 4, holes can be injected also into thehole-transport material having a deep HOMO level, such as PCzN2, withoutany barrier. Thus, it was found that it is a blue light-emitting devicethat has low driving voltage and favorable emission efficiency.

FIG. 41 is a graph showing a change in luminance over driving time at acurrent density of 50 mA/cm². As shown in FIG. 41 , the light-emittingdevice 4, which is a light-emitting device of one embodiment of thepresent invention, was found to be a light-emitting device with afavorable lifetime with a small reduction in luminance over theaccumulated driving time.

Device Example 5

In this example, light-emitting devices of one embodiment of the presentinvention will be described. The structural formulae of organiccompounds used in the light-emitting devices of this example are shownbelow.

(Fabricating Method of Light-Emitting Device 30)

First, a film of indium tin oxide containing silicon oxide (ITSO) wasformed over a glass substrate by a sputtering method, so that the firstelectrode 101 was formed. Note that the thickness was 110 nm and thearea of the electrode was 2 mm×2 mm.

Next, in pretreatment for forming the light-emitting device over thesubstrate, the surface of the substrate was washed with water and bakedat 200° C. for one hour, and then UV ozone treatment was performed for370 seconds.

After that, the substrate was transferred into a vacuum evaporationapparatus in which the pressure was reduced to about 10′ Pa, vacuumbaking at 170° C. for 30 minutes was performed in a heating chamber inthe vacuum evaporation apparatus, and then the substrate was naturallycooled down for about 30 minutes.

Next, the substrate provided with the first electrode 101 was fixed to asubstrate holder provided in the vacuum evaporation apparatus such thatthe side on which the first electrode 101 was formed faced downward, andthen N,N-bis(4-biphenyl)-6-phenylbenzo[b]naphtho[1,2-d]furan-8-amine(abbreviation: BBABnf) represented by Structural formula (i) shown aboveand NDP-9 (produced by Analysis Atelier Corporation, material serial No.1S20170124) were deposited by co-evaporation to a thickness of 10 nm onthe first electrode 101 at a weight ratio of 1:0.1 (=BBABnf:NDP-9) by anevaporation method using resistance heating, whereby the hole-injectionlayer 111 was formed.

Subsequently, over the hole-injection layer 111, BBABnf was deposited asthe first hole-transport layer 112-1 by evaporation to a thickness of 10nm, and then 3,3′-(naphthalene-1,4-diyl)bis(9-phenyl-9H-carbazole)(abbreviation: PCzN2) represented by the structural formula (ii) wasdeposited as the second hole-transport layer 112-2 by evaporation to athickness of 30 nm, whereby the hole-transport layer 112 was formed.

Then, 7-[4-(10-phenyl-9-anthryl)phenyl]-7H-dibenzo[c,g]carbazole(abbreviation: cgDBCzPA) represented by the structural formula (iii) andN,N′-(pyrene-1,6-diyl)bis[(6,N-diphenylbenzo[b]naphtho[1,2-d]furan)-8-amine](abbreviation: 1,6BnfAPrn-03) represented by the structural formula (iv)were deposited to a thickness of 25 nm by co-evaporation at a weightratio of 1:0.03 (=cgDBCzPA:1,6BnfAPrn-03), whereby the light-emittinglayer 113 was formed.

After that, over the light-emitting layer 113, cgDBCzPA was deposited byevaporation to a thickness of 15 nm, and then2,9-bis(naphthalen-2-yl)-4,7-diphenyl-1,10-phenanthroline (abbreviation:NBPhen) represented by the structural formula (v) was deposited byevaporation to a thickness of 10 nm, whereby the electron-transportlayer 114 was formed.

After the formation of the electron-transport layer 114, lithiumfluoride (LiF) was deposited by evaporation to a thickness of 1 nm toform the electron-injection layer 115, and then aluminum was depositedby evaporation to a thickness of 200 nm to form the second electrode102, whereby a light-emitting device 30 of this example was fabricated.

(Fabricating Method of Light-Emitting Device 50)

A light-emitting device 50 was fabricated in a manner similar to that ofthe light-emitting device 30 except that the thickness of the secondhole-transport layer 112-2 in the light-emitting device 30 was 50 nm.

(Fabricating Method of Light-Emitting Device 70)

A light-emitting device 70 was fabricated in a manner similar to that ofthe light-emitting element 30 except that the thickness of the secondhole-transport layer 112-2 in the light-emitting device 30 was 70 nm.

(Fabricating Method of Light-Emitting Device 80)

A light-emitting device 80 was fabricated in a manner similar to that ofthe light-emitting element 30 except that the thickness of the secondhole-transport layer 112-2 in the light-emitting device 30 was 80 nm.

(Fabricating Method of Light-Emitting Device 90)

A light-emitting device 90 was fabricated in a manner similar to that ofthe light-emitting element 30 except that the thickness of the secondhole-transport layer 112-2 in the light-emitting device 30 was 90 nm.

(Fabricating Method of Light-Emitting Device 100)

A light-emitting device 100 was fabricated in a manner similar to thatof the light-emitting element 30 except that the thickness of the secondhole-transport layer 112-2 in the light-emitting device 30 was 100 nm.

(Fabricating Method of Light-Emitting Device 110)

A light-emitting device 110 was fabricated in a manner similar to thatof the light-emitting element 30 except that the thickness of the secondhole-transport layer 112-2 in the light-emitting device 30 was 110 nm.

(Fabricating Method of Light-Emitting Device 130)

A light-emitting device 130 was fabricated in a manner similar to thatof the light-emitting element 30 except that the thickness of the secondhole-transport layer 112-2 in the light-emitting device 30 was 130 nm.

The light-emitting device 30 to the light-emitting device 130 were eachsubjected to sealing with a glass substrate (a sealant was applied tosurround the device, followed by UV treatment and one-hour heattreatment at 80° C. at the time of sealing) in a glove box in a nitrogenatmosphere so that the light-emitting device is not exposed to the air,and then the reliabilities of these light-emitting devices weremeasured. Note that the measurement was performed at room temperature.

FIG. 42 is a graph showing a change in luminance over driving time ofthe light-emitting device 30 to the light-emitting device 130 at acurrent density of 50 mA/cm². As shown in FIG. 42 , it was found thatthe light-emitting device of one embodiment of the present invention wasa light-emitting device the lifetime of which was not influenced by anincrease in the thickness of the second hole-transport layer 112-2.Thus, it was found that the light-emitting device of the presentinvention was a light-emitting device in which the optical path was ableto be easily adjusted by changing the thickness of the secondhole-transport layer 112-2.

Synthesis Example 1

In this synthesis example, a method for synthesizing4-[4′-(carbazol-9-yl)biphenyl-4-yl]-4′,4″-diphenyltriphenylamine(abbreviation: YGTBi1BP), a substance that can be used as the organiccompound of the hole-injection layer 111 in the light-emitting device ofone embodiment of the present invention, will be described in detail.The structural formula of YGTBi1BP is shown below.

After 10 g (20 mmol) ofN,N-di(4-biphenyl)-4-(4,4,5,5-tetramethyl-1,3,2-dioxaborolane-2-yl)aniline,8.0 g (20 mmol) of 9-(4′-bromobiphenyl-4-yl)carbazole, 0.12 g (0.40mmol) of tri(ortho-tolyl)phosphine, 30 mL of an aqueous solution ofpotassium carbonate (potassium carbonate 5.5 g, 40 mmol), 120 mL oftoluene, and 40 mL of ethanol were put into a 200 mL three-neck flaskequipped with a reflux pipe and mixed and the mixture was degassed underreduced pressure, the air in the system was replaced with nitrogen. Thismixture was heated at 60° C., and 44 mg (0.20 mmol) of palladium(II)acetate was added to the mixture. The mixture was stirred at 90° C. for6 hours. The obtained mixture was subjected to suction filtration. Waterwas added to the obtained filtrate to separate an aqueous layer and anorganic layer, and the aqueous layer was subjected to extraction withtoluene. The obtained extracted solution and the organic layer werecombined, washed with water and a saturated saline solution, and driedwith magnesium sulfate. This mixture was subjected to gravity filtrationand the obtained filtrate was concentrated to give a pale brown solid.This solid was purified by high performance liquid chromatography (HPLC)(mobile phase: chloroform) to give 10 g of a target pale yellow solid ina yield of 70%.

By a train sublimation method, 10 g of the obtained solid was sublimatedand purified. In the sublimation purification, the solid was heated at365° C. for 15 hours under a pressure of 3.4 Pa with a flow of argon at15 mL/min. After the sublimation purification, 8.7 g of a target paleyellow solid was obtained at a collection rate of 87%. The synthesisscheme of this synthesis is shown below.

The numeric data of ¹H-NMR of the obtained solid are shown below and ¹HNMR charts are shown in FIGS. 43(A) and 43(B). Note that FIG. 43(B) is achart showing an enlarged view of the range of 7.1 ppm to 8.3 ppm inFIG. 43(A). These indicate that YGTBi1BP was obtained in this synthesisexample.

¹H NMR (chloroform-d, 500 MHz): δ=8.17 (d, J=7.5 Hz, 2H), 7.88 (d, J=8.5Hz, 2H), 7.78 (d, J=, 8.0 Hz, 2H), 7.74 (d, J=8.0 Hz, 2H), 7.66 (d,J=8.0 Hz, 2H), 7.62-7.61 (m, 6H), 7.55 (d, J=8.5 Hz, 4H), 7.50 (d, J=8.0Hz, 2H), 7.46-7.43 (m, 6H), 7.35-7.28 (m, 10H).

Next, the ultraviolet-visible absorption spectra (hereinafter, simplyreferred to as “absorption spectra”) and emission spectra of a toluenesolution and a solid thin film of YGTBi1BP were measured. The solid thinfilm was formed over a quartz substrate by a vacuum evaporation method.For the measurement of the absorption spectra, UV-visiblespectrophotometers (solution: V-550 manufactured by JASCO Corporation,thin film: U-4100 manufactured by Hitachi High-Technologies Corporation)were used. Note that the absorption spectrum of the solution wascalculated by subtracting the absorption spectrum measured by puttingonly toluene in a quartz cell, and the absorption spectrum of the thinfilm was calculated from an absorbance (−log₁₀[% T/(100−% R)]) obtainedfrom a transmittance and a reflectance of the substrate and the thinfilm. Note that % T represents transmittance and % R representsreflectance. The emission spectra were measured using a fluorescencespectrophotometer (FS920 manufactured by Hamamatsu Photonics K.K.).

FIG. 44 shows the obtained measurement results of the absorptionspectrum and the emission spectrum of the toluene solution. FIG. 45shows the measurement results of the absorption spectrum and theemission spectrum of the solid thin film.

According to the results of FIG. 44 , the toluene solution of YGTBi1BPexhibited an absorption peak at around 351 nm and an emission wavelengthpeak at 417 nm (excitation wavelength: 350 nm). According to the resultsof FIG. 45 , the solid thin film of YGTBi1BP exhibited absorption peaksat around 356 nm, 296 nm, and 245 nm and an emission wavelength peak ataround 437 nm (excitation wavelength: 360 nm).

The HOMO level and the LUMO level of YGTBi1BP were calculated on thebasis of a cyclic voltammetry (CV) measurement. The calculation methodis shown below.

An electrochemical analyzer (ALS model 600A or 600C, manufactured by BASInc.) was used as a measurement apparatus. To prepare a solution for theCV measurement, dehydrated dimethylformamide (DMF) (produced bySigma-Aldrich Inc., 99.8%, catalog No. 22705-6) was used as a solvent,tetra-n-butylammonium perchlorate (n-Bu₄NClO₄) (produced by TokyoChemical Industry Co., Ltd., catalog No. T0836) as a supportingelectrolyte was dissolved at a concentration of 100 mmol/L, and theobject to be measured was also dissolved at a concentration of 2 mmol/L.

A platinum electrode (PTE platinum electrode, manufactured by BAS Inc.)was used as a working electrode, another platinum electrode (Pt counterelectrode for VC-3 (5 cm), manufactured by BAS Inc.) was used as anauxiliary electrode, and an Ag/Ag⁺ electrode (RE7 reference electrodefor non-aqueous solvent, manufactured by BAS Inc.) was used as areference electrode. Note that the measurement was performed at roomtemperature (20° C. to 25° C.).

In addition, the scan speed in the CV measurement was fixed to 0.1V/sec, and an oxidation potential Ea [V] and a reduction potential Ec[V] with respect to the reference electrode were measured. Ea was anintermediate potential of an oxidation-reduction wave, and Ec was anintermediate potential of a reduction-oxidation wave. Here, since thepotential energy of the reference electrode used in this example withrespect to the vacuum level is known to be −4.94 [eV], the HOMO leveland the LUMO level can be calculated by the following formulae: HOMOlevel [eV]=−4.94−Ea and LUMO level [eV]=−4.94−Ec.

As a result, the HOMO level of YGTBi1BP was found to be −5.47 eVFurthermore, the LUMO level was found to be −2.34 eV.

When CV measurement was repeated 100 times and the peak intensities ofan oxidation-reduction wave at the 100th cycle and anoxidation-reduction wave at the first cycle were compared, 83% was keptin the Ea measurement and 83% was kept in the Ec measurement, whichshowed that YGTBi1BP was an organic compound having extremely highresistance to oxidation and reduction.

Note that YGTBi1BP can be synthesized under conditions similar to thoseof the above synthesis scheme, in which the borane compound is replacedwith 4′-bromotri(4-biphenylyl)amine and halide is replaced with4-(9H-carbazol-9-yl)phenylboronic acid, as shown in the followingsynthesis scheme.

Synthesis Example 2

In this synthesis example, a method for synthesizing4-[4′-(carbazol-9-yl)biphenyl-4-yl]-4′-(2-naphthyl)-4″-phenyltriphenylamine(abbreviation: YGTBiβNB), a substance that can be used as the organiccompound of the hole-injection layer 111 in the light-emitting device ofone embodiment of the present invention, will be described. Thestructural formula of YGTBiβNB is shown below.

Step 1: Synthesis ofN-[4-(4,4,5,5-tetramethyl-1,3,2-dioxaborolane-2-yl)phenyl]-(1,1′-biphenyl)-4-amine

Into a 200 mL three-neck flask equipped with a reflux pipe were put 6.4g (20 mmol) of N-(4-bromophenyl)-4-biphenylamine, 5.1 g (20 mmol) ofbis(pinacolato)diboron, 3.9 g (40 mmol) of potassium acetate, and 100 mLof 1,4-dioxane, the mixture was degassed under reduced pressure, andthen the air in the system was replaced with nitrogen. To the obtainedmixture was added 0.16 g (0.20 mmol) of[1,1′-bis(diphenylphosphino)ferrocene]palladium(II) dichloridedichloromethane adduct, and the resulting mixture was refluxed for 7hours. Water was added to the obtained mixture to separate an aqueouslayer and an organic layer, and then the aqueous layer was subjected toextraction with toluene. The obtained extracted solution and the organiclayer were combined, washed with water and a saturated saline solution,and dried with magnesium sulfate. This mixture was subjected to gravityfiltration and the obtained filtrate was concentrated to give a brownsolid. The obtained solid was recrystallized with ethanol to give 3.2 gof a pale brown solid in a yield of 43%. The synthesis scheme of Step 1is shown below.

The numeric data of ¹H NMR of the obtained solid are shown below. Theseindicate thatN-[4-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)phenyl]-(1,1′-biphenyl)-4-amine,which was the target compound, was obtained in this synthesis step.

¹H NMR (chloroform-d, 500 MHz): δ=7.72 (d, J=9.0 Hz, 2H), 7.57 (d, J=8.0Hz, 2H), 7.53 (d, J=8.5 Hz, 2H), 7.42 (t, J=7.5 Hz, 2H), 7.31 (t, J=7.5Hz, 1H), 7.20 (d, J=8.5 Hz, 2H), 7.06 (d, J=8.5 Hz, 2H), 5.93 (s, 1H),1.34 (s, 12H).

Step 2: Synthesis of4-[4′-(carbazol-9-yl)biphenyl-4-yl]-4′-biphenylamine

Into a 200 mL three-neck flask equipped with a reflux pipe were put 3.2g (8.6 mmol) ofN-[4-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)phenyl]-(1,1′-biphenyl)-4-amine,which was obtained in Step 1, 3.4 g (8.6 mmol) of9-(4′-bromo-4-biphenylyl)carbazole, 52 mg (0.17 mmol) oftri(ortho-tolyl)phosphine, 10 mL of an aqueous solution of potassiumcarbonate (2.0 mol/L), 60 mL of toluene, and 25 mL of ethanol, themixture was degassed under reduced pressure, and then the air in thesystem was replaced with nitrogen. To the obtained mixture was added 24mg (0.11 mmol) of palladium(II) acetate, and the mixture was refluxedfor 11 hours. After the reflux, the precipitated solid was collected bysuction filtration and the obtained sold was washed with toluene,ethanol, and water to give 4.6 g of a target gray solid in a yield of93%. The synthesis scheme of Step 2 is shown below.

The numeric data of ¹H-NMR of the obtained solid are shown below and¹H-NMR charts are shown in FIGS. 46(A) and 46(B). Note that FIG. 46(B)is a chart showing an enlarged view of the range of 5.8 ppm to 8.3 ppmin FIG. 46(A). These indicate that4-[4′-(carbazol-9-yl)biphenyl-4-yl]-4′-biphenylamine, which was thetarget compound, was obtained in this synthesis step.

¹H NMR (chloroform-d, 500 MHz): δ=8.17 (d, J=7.5 Hz, 2H), 7.87 (d, J=8.5Hz, 2H), 7.75 (dd, J=9.5, 8.0 Hz, 4H), 7.66 (d, J=8.0 Hz, 2H), 7.63 (d,J=8.5 Hz, 2H), 7.59 (d, J=7.0 Hz, 2H), 7.56 (d, J=8.0 Hz, 4H), 7.50 (d,J=8.5 Hz, 2H), 7.45-7.42 (m, 4H), 7.33-7.29 (m, 3H), 7.24-7.21 (m, 4H),5.91 (s, 1H).

Step 3: Synthesis of4-[4′-(carbazol-9-yl)biphenyl-4-yl]-4′-(2-naphthyl)-4″-phenyltriphenylamine(abbreviation: YGTBiβNB)

Into a 200 mL three-neck flask equipped with a reflux pipe were put 0.85g (1.5 mmol) of 4-[4′-(carbazol-9-yl)biphenyl-4-yl]-4′-biphenylamine,which was obtained in Step 2, 0.43 g (1.5 mmol) of2-(4-bromophenyl)naphthalene, 11 mg (30 μmol) ofdi-tert-butyl(1-methyl-2,2-diphenylcyclopropyl)phosphine (product name:cBRIDP (registered trademark)), 0.29 g (3.0 mmol) of sodiumtert-butoxide, and 100 mL of toluene, the mixture was degassed underreduced pressure, and then the air in the system was replaced withnitrogen. To the obtained mixture was added 8 mg (15 μmol) ofbis(dibenzylideneacetone)palladium(0), and the mixture was refluxed for8 hours. Water was added to the obtained mixture to separate an aqueouslayer and an organic layer, and then the aqueous layer was subjected toextraction with toluene. The obtained extracted solution and the organiclayer were combined, washed with water and a saturated saline solution,and dried with magnesium sulfate. This mixture was subjected to gravityfiltration and the obtained filtrate was concentrated to give 0.83 g ofa brown solid. The synthesis scheme of Step 3 is shown below.

By a train sublimation method, 0.83 g of the obtained solid wassublimated and purified. In the sublimation purification, the solid washeated at 345° C. for 15 hours under a pressure of 3.8 Pa with a flow ofargon at 15 mL/min. After the sublimation purification, 0.49 g of atarget pale yellow solid was obtained at a collection rate of 59%.

The numeric data of ¹H NMR of the obtained solid are shown below and ¹HNMR charts are shown in FIGS. 47(A) and 47(B). Note that FIG. 47(B) is achart showing an enlarged view of the range of 7.2 ppm to 8.3 ppm inFIG. 47(A). These indicate that YGTBiβNB, which was the target compound,was obtained in this synthesis example.

¹H NMR (chloroform-d, 500 MHz): δ=8.17 (d, J=8.0 Hz, 2H), 8.05 (d, J=1.0Hz, 1H), 7.93-7.86 (m, 5H), 7.79-7.75 (m, 5H), 7.67 (t, J=8.0 Hz, 4H),7.63-7.61 (m, 4H), 7.56 (d, J=8.5 Hz, 2H), 7.52-7.42 (m, 8H), 7.35-7.28(m, 9H).

Next, absorption spectra and emission spectra of a toluene solution anda solid thin film of YGTBiβNB were measured. The measurement method,apparatus, and conditions are the same as those of Synthesis example 1;therefore, repeated description will be omitted.

FIG. 48 shows the obtained measurement results of the absorptionspectrum and the emission spectrum of the toluene solution. FIG. 49shows the measurement results of the absorption spectrum and theemission spectrum of the solid thin film.

According to the results of FIG. 48 , the toluene solution of YGTBiβNBexhibited an absorption peak at around 359 nm and an emission wavelengthpeak at 419 nm (excitation wavelength: 350 nm). According to the resultsof FIG. 49 , the solid thin film of YGTBiβNB exhibited absorption peaksat around 365 nm, 295 nm, and 245 nm and an emission wavelength peak ataround 437 nm (excitation wavelength: 360 nm).

The HOMO level and the LUMO level of YGTBiβNB were calculated on thebasis of a cyclic voltammetry (CV) measurement. The calculation methodis similar to that described in Synthesis example 1.

As a result, the HOMO level of YGTBiβNB was found to be −5.47 eV.Furthermore, the LUMO level was found to be −2.35 eV.

When CV measurement was repeated 100 times and the peak intensities ofan oxidation-reduction wave at the 100th cycle and anoxidation-reduction wave at the first cycle were compared, 85% of thepeak intensity was kept in the Ea measurement and 95% of the peakintensity was kept in the Ec measurement, which showed that YGTBiβNB hadextremely high resistance to oxidation and reduction.

Synthesis Example 3

In this synthesis example, a method for synthesizing4,4′-diphenyl-4″-(9-phenyl-9H-fluoren-9-yl)triphenylamine (abbreviation:BBAFLP), a substance that can be used as the organic compound of thehole-injection layer 111 in the light-emitting device of one embodimentof the present invention, will be described. The structure of BBAFLP isshown below.

Into a 100 mL three-neck flask were put 1.62 g (5.03 mmol) ofbis(4-biphenylyl)amine, 2.00 g (5.03 mmol) of9-(4-bromophenyl)-9-phenylfluoren, 0.97 g (10.1 mmol) of sodiumtert-butoxide, 29 mg (0.050 mmol) ofbis(dibenzylideneacetone)palladium(0), 31 mg (0.10 mmol) oftris(o-tolyl)phosphine, and 25 mL of toluene. The mixture was degassedby being stirred while the pressure was reduced, and the air in theflask was replaced with nitrogen. This mixture was stirred under anitrogen stream at 110° C. for 5.5 hours. After this mixture was cooledto room temperature, 25 ml of toluene was added, heating was performedagain so that the precipitated solid was dissolved, and purification wasperformed with Celite/alumina/Florisil/Celite. The obtained filtrate wasconcentrated, and then recrystallization with ethyl acetate wasperformed to give 2.61 g of a target white solid in a yield of 81%. Thesynthesis scheme of the above synthesis method is shown below.

By the train sublimation method, 2.53 g of the obtained white solid wassublimated and purified. The sublimation purification was performed byheating at 275° C. under the conditions where the pressure was 2.4 Paand the argon flow rate was 10 mL/min. After the purification bysublimation, 1.29 g of a white solid of BBAFLP was obtained at acollection rate of 51%.

Analysis results by nuclear magnetic resonance spectroscopy (′H NMR) ofthe obtained white solid are shown below. In addition, ¹H NMR charts areshown in FIGS. 50(A) and 50(B). Note that FIG. 50(B) is a chart showingan enlarged view of the range of 6.9 ppm to 7.9 ppm in FIG. 50(A). Theresults show that BBAFLP was obtained in this synthesis example.

¹H NMR (CDCl₃, 500 MHz): δ=7.00 (d, J=8.6 Hz, 2H), δ=7.11 (d, J=9.2 Hz,2H), δ=7.16 (d, J=8.6 Hz, 4H), δ=7.20-7.24 (m, 5H), δ=7.29 (q, J=13.2Hz, 7.5 Hz, 4H), δ=7.37 (ddd, J=7.5 Hz, 1.1 Hz, 2H), δ=7.41-7.49 (m,10H), δ=7.56 (d, J=8.1 Hz, 4H), δ=7.77 (d, J=7.5 Hz, 2H).

Synthesis Example 4

In this synthesis example, a method for synthesizing4-[4-(9-phenyl-9H-fluoren-9-yl)phenyl]-4′,4″-diphenyltriphenylamine(abbreviation: BBAFLBi), a substance that can be used as the organiccompound of the hole-injection layer 111 in the light-emitting device ofone embodiment of the present invention, will be described. Note thatthe structural formula of BBAFLBi is shown below.

Step 1: Synthesis of 4-(9-phenyl-9H-fluoren-9-yl)phenylboronic Acid

Into a 500 mL three-neck flask was put 15.89 g (40 mmol) of9-(4-bromophenyl)-9-phenyl-9H-fluorene, the mixture was degassed underreduced pressure, and the air in the flask was replaced with nitrogen.In the flask, 200 ml of dehydrated tetrahydrofuran (abbreviation: THF)was added. After the mixture was cooled to approximately −78° C. whilebeing stirred, 30 mL (48 mmol) of an n-butyllithium hexane solution at1.59 mol/L was dripped to the mixture, and then the temperature of themixture was raised to −40° C. and stirred for 1 hour. After that, 50 mlof dehydrated THF was added and the mixture was cooled to approximately−78° C. again, and then 6.4 ml (57 mmol) of trimethylborate was dripped.The temperature of the mixture was raised to room temperature andstirred for 16 hours. Then, 25 ml of water and 30 ml of 1N hydrochloricacid were added to the solution, the solution was stirred, an organiclayer and an aqueous layer were separated, and the obtained organiclayer was washed with 100 ml of a saturated solution of sodiumbicarbonate once and washed with 100 ml of a saturated saline solutiononce. After the washing, the solution was dried with magnesium sulfate,concentrated, and recrystallized with toluene to give 10.1 g of a WhiteSolid in a Yield of 70%. The Synthesis Scheme of Step 1 is shown below.

Step 2: Synthesis of BBAFLBi

Into a 200 mL three-neck flask were added 2.53 g (7 mmol) of4-(9-phenyl-9H-fluoren-9-yl)phenylboronic acid, 3.34 g (7 mmol) of4-bromo-4′,4″-diphenyltriphenylamine, 2.90 g (7 mmol) of potassiumcarbonate, 70 mL of toluene, 12.5 mL of ethanol, and 10.5 mL of water.The mixture was degassed by being stirred while the pressure wasreduced, and the air in the flask was replaced with nitrogen. To thismixture were added 15.7 mg (0.07 mmol) of palladium acetate and 42.2 mg(0.07 mmol) of tris(o-tolyl)phosphine, and stirring was performed undera nitrogen stream at 85° C. for 6 hours. After the mixture was cooled toroom temperature, the precipitated solid was separated by filtration,the obtained solution (filtrate) was washed with 100 ml of water twiceand washed with 50 ml of saturated brine once, and then, moisture wasremoved with magnesium sulfate. The obtained solid and the solidprecipitated after the reaction and separated by filtration werecombined, 300 ml of toluene was added, heating was performed so that thesolid was dissolved, and purification was performed withCelite/alumina/Florisil/Celite. The obtained filtrate was concentrated,ethanol was added, and recrystallization was performed to give 4.54 g ofa white solid in a yield of 89%. The synthesis scheme of Step 2 is shownbelow.

By the train sublimation method, 4.39 g of the obtained white solid wassublimated and purified. The sublimation purification was performed byheating at 320° C. under the conditions where the pressure was 3.5 Paand the argon flow rate was 15 mL/min. After the purification bysublimation, 2.73 g of a white solid of BBAFLBi was obtained at acollection rate of 62%.

Analysis results by nuclear magnetic resonance spectroscopy (′H NMR) ofthe obtained white solid are shown below. In addition, ¹H NMR charts areshown in FIGS. 51(A) and 51(B). Note that FIG. 51(B) is a chart showingan enlarged view of the range of 6.9 ppm to 7.9 ppm in FIG. 51(A). Theresults show that BBAFLBi was obtained in this synthesis example.

¹H NMR (CDCl₃, 500 MHz): δ=7.17-7.28 (m, 13H), δ=7.31 (dd, J=12.6 Hz,7.4 Hz, 4H), δ=7.37 (dd, J=7.5 Hz, 1.1 Hz, 4H), δ=7.40-7.47 (m, 10H),δ=7.51 (d, J=8.6 Hz, 4H) δ=7.58 (d, J=8.1 Hz, 4H) δ=7.78 (d, J=7.4 Hz,2H).

Synthesis Example 5

In this synthesis example, a method for synthesizing4,4′-diphenyl-3″-(9-phenylfluoren-9-yl)triphenylamine (abbreviation:mBBAFLP), a substance that can be used as the organic compound of thehole-injection layer 111 in the light-emitting device of one embodimentof the present invention, will be described. Note that the structure ofmBBAFLP is shown below.

Into a 300 mL three-neck flask were put 2.67 g (8.31 mmol) ofbis(4-biphenylyl)amine, 3.00 g (7.55 mmol) of9-(3-bromophenyl)-9-phenylfluoren, 1.88 g (16.8 mmol) of sodiumtert-butoxide, and 40 mL of toluene. The mixture was degassed by beingstirred while the pressure was reduced, and the air in the flask wasreplaced with nitrogen. To this mixture were added 0.2 mL oftri-tert-butylphosphine (10 wt % hexane solution) and 45 mg (0.078 mmol)of bis(dibenzylideneacetone)palladium(0) and then, stirring wasperformed for 3 hours at 110° C. under a nitrogen stream. After thestirring, the mixture was cooled to room temperature, and a solid wasseparated by filtration. The obtained filtrate was subjected to suctionfiltration through Celite and Florisil. The filtrate was concentrated,ethanol was added, and recrystallization was performed. The obtainedwhite crystal was purified by silica gel column chromatography(developing solvent: toluene) to give 4.58 g of a target white solid ina yield of 95%. The synthesis scheme of the above synthesis method isshown below.

By the train sublimation method, 2.00 g of the obtained white solid wassublimated and purified. The sublimation purification was performed byheating at 270° C. under the conditions where the pressure was 2.9 Paand the argon flow rate was 5 mL/min. After the purification bysublimation, 1.87 g of a white solid of mBBAFLP was obtained at acollection rate of 94%.

Analysis results by nuclear magnetic resonance spectroscopy (¹H NMR) ofthe obtained white solid are shown below. In addition, ¹H NMR charts areshown in FIGS. 52(A) and 52(B). Note that FIG. 52(B) is a chart showingan enlarged view of the range of 6.5 ppm to 8.0 ppm in FIG. 52(A). Theresults show that mBBAFLP was obtained in this synthesis example.

¹H NMR (CDCl₃, 500 MHz): δ=6.75 (d, J=8.0 Hz, 1H), δ=6.99 (d, J=7.0 Hz,1H), δ=7.07 (q, J=7.7 Hz, 1H), δ=7.13-7.20 (m, 11H), δ=7.23 (d, J=7.5Hz, 1H) δ=7.34 (t, J=8.0 Hz, 6H), δ=7.42 (s, 1H), δ=7.45 (t, J=8.3 Hz,7H), δ=7.57 (d, J=7.5, 4H), δ=7.74 (d, J=7.5, 2H).

Synthesis Example 6

In this synthesis example, a method for synthesizing4-[3-(9-phenyl-9H-fluoren-9-yl)phenyl]-4′,4″-diphenyltriphenylamine(abbreviation: mpBBAFLBi), a substance that can be used as the organiccompound of the hole-injection layer 111 in the light-emitting device ofone embodiment of the present invention, will be described. Note thatthe structural formula of mpBBAFLBi is shown below.

Into a 200 mL three-neck flask were added 2.0 g (5.0 mmol) of9-(3-bromophenyl)-9-phenyl-9H-fluorene, 2.6 g (5.0 mmol) of2-{4-[di(4-biphenylyl)amino]phenyl}-4,4,5,5-tetramethyl-1,3,2-dioxaborolan,30 mg (0.10 mmol) of tri(ortho-tolyl)phosphine, and 2.8 g (20 mmol) ofpotassium carbonate, and the air in the flask was replaced withnitrogen. To the mixture were added 15 mL of toluene, 10 mL of ethanol,and 10 mL of water, and the mixture was degassed by being stirred underreduced pressure. To this mixture was added 11 mg (0.050 mmol) ofpalladium(II) acetate and the mixture was stirred at 80° C. under anitrogen stream for 2 hours.

After the stirring, the mixture was subjected to suction filtration,whereby a solid was collected. The solid was dissolved in heated tolueneand subjected to suction filtration through Celite, alumina, andFlorisil. A solid obtained by concentration of the filtrate wasrecrystallized with toluene to give 2.7 g of a target white solid in ayield of 74%. The synthesis scheme of the above synthesis method isshown below.

By the train sublimation method, 2.6 g of the obtained white solid wassublimated and purified. The sublimation purification was performed byheating the white solid at 280° C. under the conditions where thepressure was 3.5 Pa and the argon flow rate was 5.0 mL/min. After thepurification by sublimation, 2.3 g of a pale yellow solid was obtainedat a collection rate of 88%.

Analysis results by nuclear magnetic resonance (′H NMR) spectroscopy ofthe obtained pale yellow solid are shown below. In addition, ¹H NMRcharts are shown in FIGS. 53(A) and 53(B). Note that FIG. 53(B) is achart showing an enlarged view of the range of 7.0 ppm to 8.0 ppm inFIG. 53(A). The results show that mpBBAFLBi was obtained in thissynthesis example.

¹H NMR (DMSO, 300 MHz): δ=7.06-7.49 (m, 29H), 7.59-7.64 (m, 8H), 7.90(d, J=7.8 Hz, 2H)

Next, absorption spectra and emission spectra of a toluene solution anda solid thin film of mpBBAFLBi were measured. Note that the measurementmethod, apparatus, and conditions are the same as those of Synthesisexample 1; therefore, repeated description will be omitted.

FIG. 54 shows the obtained measurement results of the absorptionspectrum and the emission spectrum of the toluene solution. FIG. 55shows the measurement results of the absorption spectrum and theemission spectrum of the solid thin film.

According to the results of FIG. 54 , the toluene solution of mpBBAFLBiexhibited an absorption peak at around 348 nm and an emission wavelengthpeak at 394 nm (excitation wavelength: 353 nm). According to the resultsof FIG. 55 , the solid thin film of mpBBAFLBi exhibited absorption peaksat around 352 nm and 313 nm and an emission wavelength peak at around414 nm (excitation wavelength: 355 nm).

The HOMO level and the LUMO level of mpBBAFLBi were calculated on thebasis of a cyclic voltammetry (CV) measurement. The calculation methodis similar to that described in Synthesis example 1.

As a result, the HOMO level of mpBBAFLBi was found to be −5.49 eV.Furthermore, the LUMO level was found to be −2.12 eV.

When CV measurement was repeated 100 times and the peak intensities ofan oxidation-reduction wave at the 100th cycle and anoxidation-reduction wave at the first cycle were compared, 85% was keptin the Ea measurement and 93% was kept in the Ec measurement, whichshowed that mpBBAFLBi was an organic compound having extremely highresistance to oxidation and reduction.

Synthesis Example 7

In this synthesis example, a method for synthesizing4-(4-biphenylyl)-4′-(2-naphthyl)-4″-phenyltriphenylamine (abbreviation:TPBiAβNB), a substance that can be used as the organic compound of thehole-injection layer 111 in the light-emitting device of one embodimentof the present invention, will be described. The structural formula ofTPBiAβNB is shown below.

Into a 200 mL three-neck flask equipped with a reflux pipe were added3.2 g (10 mmol) of N-(4-bromophenyl)-4-biphenylamine, 2.5 g (10 mmol) of4-biphenylboronic acid, 61 mg (0.20 mmol) of tri(ortho-tolyl)phosphine,10 mL of an aqueous solution of potassium carbonate (2.0 mol/L), 70 mLof toluene, and 30 mL of ethanol, the mixture was degassed under reducedpressure, and then the air of the system was replaced with nitrogen. Tothe obtained mixture was added 22 mg (0.10 mol) of palladium(II)acetate, and the resulting mixture was refluxed for 3 hours. After thestirring, the precipitated solid was collected by suction filtration andthe obtained solid was washed with toluene, ethanol, and water to give2.69 g of a brown solid was obtained in a yield of 86%. The synthesisscheme of Step 1 is shown below.

Step 2: Synthesis of4-(4-biphenylyl)-4′-(2-naphthyl)-4″-phenyltriphenylamine (abbreviation:TPBiAβNB)

Into a 200 mL three-neck flask equipped with a reflux pipe were put 1.5g (2.7 mmol) of N-(1,1′-biphenyl)-4-yl-(1,1′:4′,1″-terphenyl)-4-4-amine,which was obtained in Step 1, 0.75 g (2.7 mmol) of2-(4-bromophenyl)naphthalene, 18 mg (0.053 mmol) ofdi-tert-butyl(1-methyl-2,2-diphenylcyclopropyl)phosphine, 0.51 g (5.3mmol) of sodium tert-butoxide, and 100 mL of toluene, the mixture wasdegassed under reduced pressure, and then the air in the system wasreplaced with nitrogen. To the obtained mixture was added 15 mg (0.027mmol) of bis(dibenzylideneacetone)palladium(0) was added, and themixture was refluxed for 8 hours. Water was added to the obtainedmixture to separate an aqueous layer and an organic layer, and then theaqueous layer was subjected to extraction with toluene. The obtainedextracted solution and the organic layer were combined, washed withwater and a saturated saline solution, and dried with magnesium sulfate.This mixture was subjected to gravity filtration and the obtainedfiltrate was concentrated to give 1.1 g of a brown solid. The synthesisscheme of Step 2 is shown below.

By a train sublimation method, 1.1 g of the obtained solid wassublimated and purified. In the sublimation purification, the solid washeated at 300° C. for 15 hours under a pressure of 3.7 Pa with a flow ofargon at 15 mL/min. After the sublimation purification, 620 mg of atarget pale yellow solid was obtained at a collection rate of 56%.

The numeric data of the obtained solid are shown below and ¹H NMR chartsare shown in FIGS. 56(A) and 56(B). Note that FIG. 56(B) is a chartshowing an enlarged view of the range of 7.2 ppm to 8.3 ppm in FIG.56(A). These indicate that TPBiAβNB, which was the target compound, wasobtained in this synthesis example.

¹H NMR (chloroform-d, 500 MHz): δ=8.04 (d, J=1.5 Hz, 1H), 7.91 (d, J=8.5Hz, 1H), 7.89 (d, J=9.5 Hz, 1H), 7.86 (d, J=8.0 Hz, 1H), 7.77 (dd, J=4.0Hz, 1.5 Hz, 1H), 7.70-7.65 (m, 8H), 7.62-7.58 (m, 4H), 7.55 (d, J=9.0Hz, 2H), 7.52-7.43 (m, 6H), 7.38-7.27 (m, 8H)

Next, absorption spectra and emission spectra of a toluene solution anda solid thin film of TPBiAβNB were measured. The measurement method,apparatus, and conditions are the same as those of Synthesis example 1;therefore, repeated description will be omitted.

FIG. 57 shows the obtained measurement results of the absorptionspectrum and the emission spectrum of the toluene solution. FIG. 58shows the measurement results of the absorption spectrum and theemission spectrum of the solid thin film.

According to the results of FIG. 57 , the toluene solution of TPBiAβNBexhibited an absorption peak at around 357 nm and an emission wavelengthpeak at 409 nm (excitation wavelength: 357 nm). According to the resultsof FIG. 58 , the solid thin film of TPBiAβNB exhibited absorption peaksat around 364 nm, 280 nm, and 253 nm and an emission wavelength peak ataround 430 nm (excitation wavelength: 370 nm).

The HOMO level and the LUMO level of TPBiAβNB were calculated on thebasis of a cyclic voltammetry (CV) measurement. The calculation methodis similar to that described in Synthesis example 1.

As a result, the HOMO level of TPBiAβNB was found to be −5.47 eV, andthe LUMO level was found to be −2.29 eV.

When CV measurement was repeated 100 times and the peak intensities ofan oxidation-reduction wave at the 100th cycle and anoxidation-reduction wave at the first cycle were compared, 89% of thepeak intensity was kept in the Ea measurement and 98% of the peakintensity was kept in the Ec measurement, which showed that TPBiAβNB hadextremely high resistance to oxidation and reduction.

Synthesis Example 8

In this synthesis example, a method for synthesizing4-(4-biphenylyl)-4′-{4-(2-naphthyl)phenyl}-4″-phenyltriphenylamine(abbreviation: TPBiAβNBi), a substance that can be used as the organiccompound of the hole-injection layer 111 in the light-emitting device ofone embodiment of the present invention, will be described. Thestructural formula of TPBiAβNBi is shown below.

Step 1: Synthesis ofN-(1,1′-biphenyl)-4-yl-(1,1′:4′,1″-terphenyl)-4-4-amine

Into a 200 mL three-neck flask equipped with a reflux pipe were added2.4 g (7.4 mmol) of N-(4-bromophenyl)-4-biphenylamine, 1.5 g (7.4 mmol)of 4-biphenylboronic acid, 47 mg (0.15 mmol) oftri(ortho-tolyl)phosphine, 7 mL (2.0 mol/L) of an aqueous solution ofpotassium carbonate, 60 mL of toluene, and 20 mL of ethanol, the mixturewas degassed under reduced pressure, and then the air in the system wasreplaced with nitrogen. To the obtained mixture was added 16 mg (74μmol) of palladium(II) acetate, and the mixture was refluxed for 3hours. After the stirring, the precipitated solid was collected bysuction filtration and the obtained solid was washed with toluene,ethanol, and water to give 2.94 g of a target gray solid in a yield of99% or higher. The synthesis scheme of Step 2 is shown below.

Step 2: Synthesis of 2-(4-chloro-biphenyl-4-yl)naphthalene

Into a 200 mL three-neck flask equipped with a reflux pipe were added2.4 g (10 mmol) of 1-chloro-4-iodobenzene, 2.5 g (10 mmol) of4-(2-naphthyl)phenylboronic acid, 61 mg (0.20 mmol) oftri(ortho-tolyl)phosphine, 20 mL (2.0 mol/L) of an aqueous solution ofpotassium carbonate, 70 mL of toluene, and 30 mL of ethanol, the solventwas degassed under reduced pressure, and the air in the flask wasreplaced with nitrogen. After heating at 60° C., 22 mg (0.10 mmol) ofpalladium(II) acetate was added, and reaction was caused by stirring at50° C. for 3 hours. After the stirring, the precipitated solid wascollected by suction filtration and washed with toluene, water, andethanol to give 2.7 g of a brown solid in a yield of 86%. The synthesisscheme of Step 2 is shown below.

The numeric data of the obtained brown solid are shown below. Theseindicate that 2-(4-chloro-biphenyl-4-yl)naphthalene was obtained in thissynthesis step.

¹H NMR (dichloromethane-d₂, 500 MHz): δ=8.13 (s, 1H), 7.96 (d, J=9.5 Hz,1H), 7.94 (d, J=9.5 Hz, 1H), 7.89 (d, J=7.0 Hz, 1H), 7.85-7.81 (m, 3H),7.72 (d, J=8.0 Hz, 2H), 7.64 (d, J=8.5 Hz, 2H), 7.55-7.49 (m, 2H), 7.46(d, J=8.0 Hz, 2H)

Step 3: Synthesis of4-(4-biphenylyl)-4′-{4-(2-naphthyl)phenyl}-4″-phenyltriphenylamine(abbreviation: TPBiAβNBi)

Into a 200 mL three-neck flask equipped with a reflux pipe were put 2.94g (7.4 mmol) of N-(1,1′-biphenyl)-4-yl-(1,1′:4′,1″-terphenyl)-4-4-amine,which was obtained in Step 1, 2.32 g (7.4 mmol) of2-(4-chloro-biphenyl-4-yl)naphthalene, which was obtained in Step 2, 52mg (0.15 mmol) ofdi-tert-butyl(1-methyl-2,2-diphenylcyclopropyl)phosphine (product name:cBRIDP (registered trademark)), 1.4 g (15 mmol) of sodium tert-butoxide,and 140 mL of xylene, the mixture was degassed under reduced pressure,and then the air in the system was replaced with nitrogen. To theobtained mixture was added 43 mg (74 μmol) ofbis(dibenzylideneacetone)palladium(0), and the mixture was refluxed for5 hours. After stirring, the precipitated solid was collected by suctionfiltration and washing with toluene, water, and ethanol was performed togive 3.8 g of a gray solid. The synthesis scheme of Step 3 is shownbelow.

By a train sublimation method, 3.8 g of the obtained solid wassublimated and purified. In the purification by sublimation, the solidwas heated at 335° C. under a pressure of 3.8 Pa for 15 hours with aflow of argon at 15 mL/min. After the sublimation purification, 2.8 g ofa target pale yellow solid was obtained at a collection rate of 74%.

The numeric data of the obtained solid are shown below and ¹H NMR chartsare shown in FIGS. 59(A) and 59(B). Note that FIG. 59(B) is a chartshowing an enlarged view of the range of 7.2 ppm to 8.3 ppm in FIG.59(A). These indicate that TPBiAβNBi, which was the target compound, wasobtained in this synthesis example.

¹H NMR (chloroform-d, 500 MHz): δ=8.10 (d, J=1.5 Hz, 1H), 7.94 (d, J=9.0Hz, 1H), 7.92 (d, J=7.5 Hz, 1H), 7.88 (d, J=7.5 Hz, 1H), 7.82-7.80 (m,3H), 7.73 (d, J=8.5 Hz, 2H), 7.68 (s, 4H), 7.66 (d, J=7.0 Hz, 2H),7.62-7.58 (m, 6H), 7.55 (d, J=8.5 Hz, 2H), 7.52-7.43 (m, 6H), 7.36 (t,J=7.0 Hz, 1H), 7.33 (t, J=7.0 Hz, 1H), 7.29-7.27 (m, 6H)

Next, absorption spectra and emission spectra of a toluene solution anda solid thin film of TPBiAβNBi were measured. The measurement method,apparatus, and conditions are the same as those of Synthesis example 1;therefore, repeated description will be omitted.

FIG. 60 shows the obtained measurement results of the absorptionspectrum and the emission spectrum of the toluene solution. FIG. 61shows the measurement results of the absorption spectrum and theemission spectrum of the solid thin film.

According to the results of FIG. 60 , the toluene solution of TPBiAβNBiexhibited an absorption peak at around 359 nm and an emission wavelengthpeak at 420 nm (excitation wavelength: 410 nm). According to the resultsof FIG. 61 , the solid thin film of TPBiAβNBi exhibited absorption peaksat around 368 nm, 295 nm, and 272 nm and an emission wavelength peak ataround 439 nm (excitation wavelength: 370 nm).

The HOMO level and the LUMO level of TPBiAβNBi were calculated on thebasis of a cyclic voltammetry (CV) measurement. The calculation methodis similar to that described in Synthesis example 1.

As a result, the HOMO level of TPBiAβNBi was found to be −5.47 eV, andthe LUMO level was found to be −2.38 eV.

When CV measurement was repeated 100 times and the peak intensities ofan oxidation-reduction wave at the 100th cycle and anoxidation-reduction wave at the first cycle were compared, 83% of thepeak intensity was kept in the Ea measurement and 95% of the peakintensity was kept in the Ec measurement, which showed that TPBiAβNBihad extremely high resistance to oxidation and reduction.

Synthesis Example 9

In this synthesis example, a method for synthesizing4,4′-diphenyl-4″-(7-phenyl)naphthyl-2-yltriphenylamine (abbreviation:BBAPβNB-03), a substance that can be used as the organic compound of thehole-injection layer 111 in the light-emitting device of one embodimentof the present invention, will be described. The structural formula ofBBAPβNB-03 is shown below.

Step 1: Synthesis of 7-bromo-2-phenylnaphthalene

Into a 200 mL three-neck flask equipped with a reflux pipe were added3.8 g (13 mmol) of 2,7-dibromonaphthalene, 2.3 g (13 mmol) ofphenylboronic acid, 81 mg (27 μmol) of tri(ortho-tolyl)phosphine, 65 mLof toluene, 30 mL of ethanol, and 15 mL of a 2M aqueous solution ofpotassium carbonate (2.0 mmol/L), the mixture was degassed under reducedpressure, and then the air in the system was replaced with nitrogen.After that, 30 mg (0.13 mmol) of palladium acetate was added, andstirring was performed at room temperature for 3 hours. A solidprecipitated in the obtained reaction mixture was removed by suctionfiltration. Water was added to the obtained filtrate to separate anaqueous layer and an organic layer, and then the aqueous layer wassubjected to extraction with toluene. The obtained extracted solutionand the organic layer were combined, washed with water and a saturatedsaline solution, and dried with magnesium sulfate. The obtained mixturewas subjected to gravity filtration and then concentrated, and theobtained residue was purified by high performance liquid chromatography(mobile phase: chloroform). Thus, 2.3 g of a white solid, which was thetarget compound, was obtained in a yield of 52%. The synthesis scheme ofStep 1 is shown below.

Step 2: Synthesis of4,4′-diphenyl-4″-(7-phenyl)naphthyl-2-yltriphenylamine (abbreviation:BBAPβNB-03)

Into a 200 mL three-neck flask equipped with a reflux pipe were put 1.8g (6.5 mmol) of 7-bromo-2-phenylnaphthalene, which was obtained in Step1, 3.5 g (6.5 mmol) ofN,N-di(4-biphenyl)-4-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)aniline,40 mg (0.13 mmol) of tri(ortho-tolyl)phosphine, 6.5 mL of an aqueoussolution of potassium carbonate (2.0 mol/L), 60 mL of toluene, and 35 mLof ethanol, the mixture was degassed under reduced pressure, and thenthe air in the system was replaced with nitrogen. To the obtainedmixture was added 14 mg (65 μmol) of palladium(II) acetate, and themixture was refluxed for 4 hours. After stirring, the precipitated solidwas removed by suction filtration. Water was added to the obtainedfiltrate to separate an aqueous layer and an organic layer, and then theaqueous layer was subjected to extraction with toluene. The obtainedextracted solution and the organic layer were combined, washed withwater and a saturated saline solution, and dried with magnesium sulfate.This mixture was subjected to gravity filtration and the obtainedfiltrate was concentrated to give 2.1 g of a brown solid. The synthesisscheme of Step 2 is shown below.

By a train sublimation method, 1.9 g of the obtained brown solid wassublimated and purified. In the sublimation purification, the solid washeated at 280° C. under a pressure of 4.1 Pa for 24 hours with a flow ofargon at 15 mL/min. After the purification by sublimation, 1.1 g of atarget pale yellow solid was obtained at a collection rate of 51%.

The numeric data of the obtained solid are shown below and ¹H NMR chartsare shown in FIGS. 62(A) and 62(B). Note that FIG. 62(B) is a chartshowing an enlarged view of the range of 7.2 ppm to 8.3 ppm in FIG.62(A). These indicate that BBAPβNB-03, which was the target compound,was obtained in this synthesis example.

¹H NMR (dichloromethane-d₂, 500 MHz): δ=8.13 (d, J=2.0 Hz, 2H), 7.95 (d,J=8.5 Hz, 2H), 7.80-7.76 (m, 4H), 7.72 (d, J=9.0 Hz, 2H), 7.62 (d, J=8.0Hz, 4H), 7.57 (d, J=8.5 Hz, 4H), 7.50 (t, J=8.0 Hz, 2H), 7.44 (t, J=8.0Hz, 4H), 7.40 (t, J=7.5 Hz, 1H), 7.33 (t, J=7.5 Hz, 2H), 7.29 (d, J=8.5Hz, 2H), 7.26 (d, J=8.5 Hz, 4H).

Next, absorption spectra and emission spectra of a toluene solution anda solid thin film of BBAPβNB-03 were measured. The measurement method,apparatus, and conditions are the same as those of Synthesis example 1;therefore, repeated description will be omitted.

FIG. 63 shows the obtained measurement results of the absorptionspectrum and the emission spectrum of the toluene solution. FIG. 64shows the measurement results of the absorption spectrum and theemission spectrum of the solid thin film.

According to the results of FIG. 63 , the toluene solution of BBAPβNB-03exhibited an absorption peak at around 352 nm and an emission wavelengthpeak at 409 nm (excitation wavelength: 352 nm). According to the resultsof FIG. 64 , the solid thin film of BBAPβNB-03 exhibited absorptionpeaks at around 359 nm, 259 nm, and 211 nm and an emission wavelengthpeak at around 430 nm (excitation wavelength: 360 nm).

The HOMO level and the LUMO level of BBAPβNB-03 were calculated on thebasis of a cyclic voltammetry (CV) measurement. The calculation methodis similar to that described in Synthesis example 1.

As a result, the HOMO level of BBAPβNB-03 was found to be −5.47 eV, andthe LUMO level was found to be −2.33 eV.

When CV measurement was repeated 100 times and the peak intensities ofan oxidation-reduction wave at the 100th cycle and anoxidation-reduction wave at the first cycle were compared, 91% of thepeak intensity was kept in the Ea measurement and 85% of the peakintensity was kept in the Ec measurement, which showed that BBAPβNB-03had extremely high resistance to oxidation and reduction.

Synthesis Example 10

In this synthesis example, a method for synthesizing4′-[4-(3-phenyl-9H-carbazol-9-yl)phenyl]tris(1,1′-biphenyl-4-yl)amine(abbreviation: YGTBi1BP-02), a substance that can be used as the organiccompound of the hole-injection layer 111 in the light-emitting device ofone embodiment of the present invention, will be described. Thestructural formula of YGTBi1BP-02 is shown below.

Step 1: Synthesis of 4′-(4-chlorophenyl)tris(1,1′-biphenyl-4-yl)amine

Into a 200 mL three-neck flask were put 8.8 g (17 mmol) of2-{4-[di(4-biphenylyl)amino]phenyl}-4,4,5,5-tetramethyl-1,3,2-dioxaborolane,4.5 g (17 mmol) of 4-bromo-4′-chlorobiphenyl, 0.15 g (0.50 mmol) oftri(ortho-tolyl)phosphine, 25 mL of an aqueous solution of potassiumcarbonate (2.0 mmol/L), 128 mL of toluene, and 32 mL of ethanol, themixture was degassed under reduced pressure, and then the air in theflask was replaced with nitrogen. To the mixture was added 39 mg (0.17mmol) of palladium(II) acetate, and stirring was performed at 60° C. for9.5 hours. After the stirring, the precipitated solid was collected bysuction filtration, and the obtained solid was washed with toluene,ethanol, and water. The washed solid was dissolved in hot toluene, theobtained solution was filtered through alumina, Florisil (Wako PureChemical Industries, Ltd., Catalog No. 066-05265), and Celite (Wako PureChemical Industries, Ltd., Catalog No. 537-02305), and the filtrate wascooled, whereby a white solid was precipitated. This white solid wascollected by suction filtration to give 6.1 g of a target substance. Asingle yellow solid obtained by concentration of the filtrate wasrecrystallized with toluene to give 3.4 g of a white solid. In total,9.5 g of a white solid was obtained in a yield of 95%. The synthesisscheme of Step 1 is shown below.

Step 2: Synthesis of4′-[4-(3-phenyl-9H-carbazol-9-yl)phenyl]tris(1,1′-biphenyl-4-yl)amine(abbreviation: YGTBi1BP-02)

Into a 200 mL three-neck flask were put 2.0 g (3.4 mmol) of4′-(4-chlorophenyl)tris(1,1′-biphenyl-4-yl)amine, which was obtained inStep 1, 0.83 g (3.4 mmol) of 3-phenyl-9H-carbazole, mg (0.10 mmol) ofdi-tert-butyl(2,2-diphenyl-1-methyl-1-cyclopropyl)phosphine(abbreviation: cBRIDP), 0.99 g (10 mmol) of sodium tert butoxide, and 35mL of mesitylene, the mixture was degassed under reduced pressure, andthen the air in the system was replaced with nitrogen. To this mixturewas added 21 mg (34 μmol) of bis(dibenzylideneacetone)palladium(II), andthe mixture was stirred at 120° C. for 8.5 hours. After the stirring,the raw material was left when reaction was checked with thin layerchromatography; therefore, 37 mg (0.10 mmol) of cBRIDP and 20 mg (33μmol) of bis(dibenzylideneacetone) palladium(II)) were added to themixture and then the mixture was heated and stirred at 150° C. for 6hours. After the heating, toluene and water were added to the obtainedmixture, the mixture was stirred, and then an organic layer of themixture was washed with water and a saturated saline solution. Anhydrousmagnesium sulfate was added to the obtained organic layer and drying wasperformed. This mixture was subjected to gravity filtration and thefiltrate was concentrated to give a brown solid. The obtained solid wasdissolved in toluene, the solution was filtered through alumina,Florisil (Wako Pure Chemical Industries, Ltd., Catalog No. 066-05265),and Celite (Wako Pure Chemical Industries, Ltd., Catalog No. 537-02305),and the obtained filtrate was concentrated to give a yellow brown solid.The solid was recrystallized with toluene to give 1.9 g of a targetyellow solid in a yield of 69%. The synthesis scheme of Step 2 is shownbelow.

¹H-NMR data of the obtained solid are shown in FIG. 65 , and the numericdata are shown below. These indicate that4′-[4-(3-phenyl-9H-carbazol-9-yl)phenyl]tris(1,1′-biphenyl-4-yl)amine(abbreviation: YGTBi1BP-02) was obtained.

¹H NMR (dichloromethane-d₂, 500 MHz): δ=7.24 (d, J=7.0 Hz, 3H), 7.26 (d,J=7.0 Hz, 3H), 7.30-7.35 (m, 4H), 7.41-7.52 (m, 8H), 7.56 (dt, J1=8.5Hz, J2=1.5 Hz, 5H), 7.63 (d, J=8.5 Hz, 4H), 7.63 (d, J=8.5 Hz, 2H),7.69-7.71 (m, 3H), 7.73-7.76 (m, 4H), 7.80 (d, J=8.5 Hz, 2H), 7.92 (dt,J1=8.0 Hz, J2=1.5 Hz, 2H), 8.21 (d, J=7.5 Hz, 1H), 8.39 (sd, J=1.0 Hz,1H).

Sublimation purification was performed on 1.9 g of the obtained solid.The sublimation purification was performed under the condition of thepressure being 1.9×10⁻³ Pa, by heating the solid to 370° C. After thesublimation purification, 0.74 g of a yellow solid, which was the targetcompound, was obtained at a collection rate of 40%.

Next, absorption spectra and emission spectra of a toluene solution anda solid thin film of YGTBi1BP-02 were measured. The measurement method,apparatus, and conditions are the same as those of Synthesis example 1;therefore, repeated description will be omitted.

FIG. 66 shows the obtained measurement results of the absorptionspectrum and the emission spectrum of the toluene solution. FIG. 67shows the measurement results of the absorption spectrum and theemission spectrum of the solid thin film.

According to the results of FIG. 66 , the toluene solution ofYGTBi1BP-02 exhibited an absorption peak at around 353 nm and anemission wavelength peak at around 419 nm (excitation wavelength: 353nm). According to FIG. 67 , the solid thin film of YGTBi1BP-02 exhibitedabsorption peaks at around 356 nm, 290 nm, 251 nm, and 207 nm, andemission wavelength peaks at around 439 nm and 453 nm (excitationwavelength: 370 nm). These results indicate that YGTBi1BP-02 emits bluelight and can also be used as a host for a light-emitting substance or ahost for a fluorescent substance in the visible region.

The HOMO level and the LUMO level of YGTBi1BP-02 were calculated basedon the basis of a cyclic voltammetry (CV) measurement. The calculationmethod is similar to that described in Synthesis example 1.

As a result, the HOMO level of YGTBi1BP-02 was found to be −5.47 eV, andthe LUMO level was found to be −2.35 eV.

When CV measurement was repeated 100 times and the peak intensities ofan oxidation-reduction wave at the 100th cycle and anoxidation-reduction wave at the first cycle were compared, 88% of thepeak intensity was kept in the Ea measurement and 96% of the peakintensity was kept in the Ec measurement, which showed that YGTBi1BP-02had extremely high resistance to oxidation and reduction.

Differential scanning calorimetry (DSC) of YGTBi1BP-02 was performedwith Pyris1DSC manufactured by PerkinElmer, Inc. The DSC was performedin the following manner: the temperature was raised from −10° C. to 360°C. at a temperature rising rate of 40° C./min and held for threeminutes; then, the temperature was decreased to −10° C. at a temperaturedecreasing rate of 100° C./min and held at −10° C. for three minutes.This operation was performed twice in succession. It was found from theDSC result of the second cycle that the glass transition point ofYGTBi1BP-02 was 142° C., that is, YGTBi1BP-02 was a substance withextremely high heat resistance.

Then, thermogravimetry-differential thermal analysis (TG-DTA) ofYGTBi1BP-02 was performed. The measurement was performed using a highvacuum differential type differential thermal balance (TG-DTA2410SA,produced by Bruker AXS K.K.). The measurement was performed underatmospheric pressure at a temperature rising rate of 10° C./min under anitrogen stream (flow rate: 200 mL/min). In thethermogravimetry-differential thermal analysis, the temperature(decomposition temperature) at which the weight obtained bythermogravimetry was reduced by 5% of the weight at the beginning of themeasurement was found to be 500° C. or higher, which shows thatYGTBi1BP-02 is a substance with high heat resistance.

REFERENCE NUMERALS

101: first electrode, 102: second electrode, 103: EL layer, 111:hole-injection layer, 112: hole-transport layer, 112-1: firsthole-transport layer, 112-2: second hole-transport layer, 113:light-emitting layer, 114: electron-transport layer, 115:electron-injection layer, 116: charge-generation layer, 117: P-typelayer, 118: electron-relay layer, 119: electron-injection buffer layer,400: substrate, 401: first electrode, 403: EL layer, 404: secondelectrode, 405: sealant, 406: sealant, 407: sealing substrate, 412: pad,420: IC chip, 501: anode, 502: cathode, 511: first light-emitting unit,512: second light-emitting unit, 513: charge-generation layer, 601:driver circuit portion (source line driver circuit), 602: pixel portion,603: driver circuit portion (gate line driver circuit), 604: sealingsubstrate, 605: sealant, 607: space, 608: wiring, 609: FPC (flexibleprinted circuit), 610: element substrate, 611: switching FET, 612:current control FET, 613: first electrode, 614: insulator, 616: ELlayer, 617: second electrode, 618: light-emitting device, 951:substrate, 952: electrode, 953: insulating layer, 954: partition layer,955: EL layer, 956: electrode, 1001 substrate, 1002 base insulatingfilm, 1003 gate insulating film, 1006 gate electrode, 1007 gateelectrode, 1008 gate electrode, 1020 first interlayer insulating film,1021 second interlayer insulating film, 1022 electrode, 1024W firstelectrode, 1024R first electrode, 1024G first electrode, 1024B firstelectrode, 1025 partition, 1028 EL layer, 1029 second electrode, 1031sealing substrate, 1032 sealant, 1033 transparent base material, 1034Rred coloring layer, 1034G green coloring layer, 1034B blue coloringlayer, 1035 black matrix, 1036 overcoat layer, 1037 third interlayerinsulating film, 1040 pixel portion, 1041 driver circuit portion, 1042peripheral portion, 2001: housing, 2002: light source, 2100: robot,2110: arithmetic device, 2101: illuminance sensor, 2102: microphone,2103: upper camera, 2104: speaker, 2105: display, 2106: lower camera,2107: obstacle sensor, 2108: moving mechanism, 3001: lighting device,5000: housing, 5001: display portion, 5002: second display portion,5003: speaker, 5004: LED lamp, 5005: operation key, 5006: connectionterminal, 5007: sensor, 5008: microphone, 5012: support, 5013: earphone,5100: cleaning robot, 5101: display, 5102: camera, 5103: brush, 5104:operation button, 5150: portable information terminal, 5151: housing,5152: display region, 5153: bend portion, 5120: dust, 5200: displayregion, 5201: display region, 5202: display region, 5203: displayregion, 7101: housing, 7103: display portion, 7105: stand, 7107: displayportion, 7109: operation key, 7110: remote controller, 7201: main body,7202: housing, 7203: display portion, 7204: keyboard, 7205: externalconnection port, 7206: pointing device, 7210: second display portion,7401: housing, 7402: display portion, 7403: operation button, 7404:external connection port, 7405: speaker, 7406: microphone, 7400: mobilephone, 9310: portable information terminal, 9311: display panel, 9312:display region, 9313: hinge, 9315: housing

This application is based on Japanese Patent Application Serial No.2018-053135 filed with Japan Patent Office on Mar. 20, 2018, the entirecontents of which are hereby incorporated herein by reference.

The invention claimed is:
 1. A light-emitting device comprising: ananode; a cathode; and a layer comprising an organic compound positionedbetween the anode and the cathode, wherein the layer comprising theorganic compound comprises a first layer, a second layer, and alight-emitting layer in order from the anode side, wherein the firstlayer comprises a first substance and a second substance, wherein thesecond layer comprises a third substance, wherein the first substance isan organic compound having a HOMO level higher than or equal to −5.8 eVand lower than or equal to −5.4 eV, wherein the second substance is asubstance having an electron-acceptor property to the first substance,wherein the third substance is an organic compound, and wherein at leasttwo substituents comprising carbazole rings bond to a naphthalene ringin the organic compound of the third substance.
 2. The light-emittingdevice according to claim 1, wherein the first substance is an organiccompound comprising an N,N-bis(4-biphenyl)amino group.
 3. Thelight-emitting device according to claim 1, comprising: a third layerbetween the first layer and the second layer, wherein the third layercomprises a fourth substance, and wherein the fourth substance is anorganic compound having a hole-transport property.
 4. The light-emittingdevice according to claim 1, comprising: a third layer between the firstlayer and the second layer, wherein the third layer comprises a fourthsubstance, and wherein the fourth substance is an organic compoundhaving a HOMO level higher than or equal to −5.8 eV and lower than orequal to −5.4 eV.
 5. The light-emitting device according to claim 3,wherein the fourth substance is the same substance as the firstsubstance.
 6. A light-emitting device comprising: an anode; a cathode;and a layer comprising an organic compound positioned between the anodeand the cathode, wherein the layer comprising the organic compoundcomprises a first layer, a second layer, and a light-emitting layer inorder from the anode side, wherein the first layer comprises a firstsubstance and a second substance, wherein the second layer comprises athird substance, wherein the first substance is an aromatic aminecomprising a substituent comprising a dibenzofuran ring or adibenzothiophene ring, wherein the second substance is a substancehaving an electron-acceptor property to the first substance, wherein thethird substance is an organic compound, and wherein at least twosubstituents comprising carbazole rings bond to a naphthalene ring inthe organic compound of the third substance.
 7. The light-emittingdevice according to claim 6, wherein the first substance is an organiccompound comprising an N,N-bis(4-biphenyl)amino group.
 8. Thelight-emitting device according to claim 6, comprising: a third layerbetween the first layer and the second layer, wherein the third layercomprises a fourth substance, and wherein the fourth substance is anorganic compound having a hole-transport property.
 9. The light-emittingdevice according to claim 6, comprising: a third layer between the firstlayer and the second layer, wherein the third layer comprises a fourthsubstance, and wherein the fourth substance is an organic compoundhaving a HOMO level higher than or equal to −5.8 eV and lower than orequal to −5.4 eV.
 10. The light-emitting device according to claim 8,wherein the fourth substance is the same substance as the firstsubstance.
 11. A light-emitting device comprising: an anode; a cathode;and a layer comprising an organic compound positioned between the anodeand the cathode, wherein the layer comprising the organic compoundcomprises a first layer, a second layer, and a light-emitting layer inorder from the anode side, wherein the first layer comprises a firstsubstance and a second substance, wherein the second layer comprises athird substance, wherein the first substance is an aromatic monoaminecomprising a naphthalene ring, wherein the second substance is asubstance having an electron-acceptor property to the first substance,wherein the third substance is an organic compound, and wherein at leasttwo substituents comprising carbazole rings bond to a naphthalene ringin the organic compound of the third substance.
 12. The light-emittingdevice according to claim 11, wherein the first substance is an organiccompound comprising an N,N-bis(4-biphenyl)amino group.
 13. Thelight-emitting device according to claim 11, comprising: a third layerbetween the first layer and the second layer, wherein the third layercomprises a fourth substance, and wherein the fourth substance is anorganic compound having a hole-transport property.
 14. Thelight-emitting device according to claim 11, comprising: a third layerbetween the first layer and the second layer, wherein the third layercomprises a fourth substance, and wherein the fourth substance is anorganic compound having a HOMO level higher than or equal to −5.8 eV andlower than or equal to −5.4 eV.
 15. The light-emitting device accordingto claim 13, wherein the fourth substance is the same substance as thefirst substance.
 16. A light-emitting device comprising: an anode; acathode; and a layer comprising an organic compound positioned betweenthe anode and the cathode, wherein the layer comprising the organiccompound comprises a first layer, a second layer, and a light-emittinglayer in order from the anode side, wherein the first layer comprises afirst substance and a second substance, wherein the second layercomprises a third substance, wherein the first substance is an aromaticmonoamine in which a 9-fluorenyl group is bonded to nitrogen through anarylene group, wherein the second substance is a substance having anelectron-acceptor property to the first substance, wherein the thirdsubstance is an organic compound, and wherein at least two substituentscomprising carbazole rings bond to a naphthalene ring in the organiccompound.
 17. The light-emitting device according to claim 16, whereinthe first substance is an organic compound comprising anN,N-bis(4-biphenyl)amino group.
 18. The light-emitting device accordingto claim 16, comprising: a third layer between the first layer and thesecond layer, wherein the third layer comprises a fourth substance, andwherein the fourth substance is an organic compound having ahole-transport property.
 19. The light-emitting device according toclaim 16, comprising: a third layer between the first layer and thesecond layer, wherein the third layer comprises a fourth substance, andwherein the fourth substance is an organic compound having a HOMO levelhigher than or equal to −5.8 eV and lower than or equal to −5.4 eV. 20.The light-emitting device according to claim 18, wherein the fourthsubstance is the same substance as the first substance.